update stb_image from 2.26 to 2.27

src/libraries/stb/stb_image.h

@@ -1,4 +1,4 @@
-/* stb_image - v2.26 - public domain image loader - http://nothings.org/stb
+/* stb_image - v2.27 - public domain image loader - http://nothings.org/stb
                                   no warranty implied; use at your own risk
 
    Do this:
@@ -48,6 +48,7 @@ LICENSE
 
 RECENT REVISION HISTORY:
 
+      2.27  (2021-07-11) document stbi_info better, 16-bit PNM support, bug fixes
       2.26  (2020-07-13) many minor fixes
       2.25  (2020-02-02) fix warnings
       2.24  (2020-02-02) fix warnings; thread-local failure_reason and flip_vertically
@@ -89,7 +90,7 @@ RECENT REVISION HISTORY:
                                            Jeremy Sawicki (handle all ImageNet JPGs)
  Optimizations & bugfixes                  Mikhail Morozov (1-bit BMP)
     Fabian "ryg" Giesen                    Anael Seghezzi (is-16-bit query)
-    Arseny Kapoulkine
+    Arseny Kapoulkine                      Simon Breuss (16-bit PNM)
     John-Mark Allen
     Carmelo J Fdez-Aguera
 
@@ -102,7 +103,7 @@ RECENT REVISION HISTORY:
     Thomas Ruf              Ronny Chevalier                         github:rlyeh
     Janez Zemva             John Bartholomew   Michal Cichon        github:romigrou
     Jonathan Blow           Ken Hamada         Tero Hanninen        github:svdijk
-                            Laurent Gomila     Cort Stratton        github:snagar
+    Eugene Golushkov        Laurent Gomila     Cort Stratton        github:snagar
     Aruelien Pocheville     Sergio Gonzalez    Thibault Reuille     github:Zelex
     Cass Everitt            Ryamond Barbiero                        github:grim210
     Paul Du Bois            Engin Manap        Aldo Culquicondor    github:sammyhw
@@ -110,11 +111,13 @@ RECENT REVISION HISTORY:
     Josh Tobin                                 Matthew Gregan       github:poppolopoppo
     Julian Raschke          Gregory Mullen     Christian Floisand   github:darealshinji
     Baldur Karlsson         Kevin Schmidt      JR Smith             github:Michaelangel007
-                            Brad Weinberger    Matvey Cherevko      [reserved]
+                            Brad Weinberger    Matvey Cherevko      github:mosra
     Luca Sas                Alexander Veselov  Zack Middleton       [reserved]
     Ryan C. Gordon          [reserved]                              [reserved]
                      DO NOT ADD YOUR NAME HERE
 
+                     Jacko Dirks
+
   To add your name to the credits, pick a random blank space in the middle and fill it.
   80% of merge conflicts on stb PRs are due to people adding their name at the end
   of the credits.
@@ -176,6 +179,32 @@ RECENT REVISION HISTORY:
 //
 // Paletted PNG, BMP, GIF, and PIC images are automatically depalettized.
 //
+// To query the width, height and component count of an image without having to
+// decode the full file, you can use the stbi_info family of functions:
+//
+//   int x,y,n,ok;
+//   ok = stbi_info(filename, &x, &y, &n);
+//   // returns ok=1 and sets x, y, n if image is a supported format,
+//   // 0 otherwise.
+//
+// Note that stb_image pervasively uses ints in its public API for sizes,
+// including sizes of memory buffers. This is now part of the API and thus
+// hard to change without causing breakage. As a result, the various image
+// loaders all have certain limits on image size; these differ somewhat
+// by format but generally boil down to either just under 2GB or just under
+// 1GB. When the decoded image would be larger than this, stb_image decoding
+// will fail.
+//
+// Additionally, stb_image will reject image files that have any of their
+// dimensions set to a larger value than the configurable STBI_MAX_DIMENSIONS,
+// which defaults to 2**24 = 16777216 pixels. Due to the above memory limit,
+// the only way to have an image with such dimensions load correctly
+// is for it to have a rather extreme aspect ratio. Either way, the
+// assumption here is that such larger images are likely to be malformed
+// or malicious. If you do need to load an image with individual dimensions
+// larger than that, and it still fits in the overall size limit, you can
+// #define STBI_MAX_DIMENSIONS on your own to be something larger.
+//
 // ===========================================================================
 //
 // UNICODE:
@@ -281,11 +310,10 @@ RECENT REVISION HISTORY:
 //
 // iPhone PNG support:
 //
-// By default we convert iphone-formatted PNGs back to RGB, even though
-// they are internally encoded differently. You can disable this conversion
-// by calling stbi_convert_iphone_png_to_rgb(0), in which case
-// you will always just get the native iphone "format" through (which
-// is BGR stored in RGB).
+// We optionally support converting iPhone-formatted PNGs (which store
+// premultiplied BGRA) back to RGB, even though they're internally encoded
+// differently. To enable this conversion, call
+// stbi_convert_iphone_png_to_rgb(1).
 //
 // Call stbi_set_unpremultiply_on_load(1) as well to force a divide per
 // pixel to remove any premultiplied alpha *only* if the image file explicitly
@@ -489,6 +517,8 @@ STBIDEF void stbi_set_flip_vertically_on_load(int flag_true_if_should_flip);
 // as above, but only applies to images loaded on the thread that calls the function
 // this function is only available if your compiler supports thread-local variables;
 // calling it will fail to link if your compiler doesn't
+STBIDEF void stbi_set_unpremultiply_on_load_thread(int flag_true_if_should_unpremultiply);
+STBIDEF void stbi_convert_iphone_png_to_rgb_thread(int flag_true_if_should_convert);
 STBIDEF void stbi_set_flip_vertically_on_load_thread(int flag_true_if_should_flip);
 
 // ZLIB client - used by PNG, available for other purposes
@@ -634,7 +664,7 @@ typedef unsigned char validate_uint32[sizeof(stbi__uint32)==4 ? 1 : -1];
 #ifdef STBI_HAS_LROTL
    #define stbi_lrot(x,y)  _lrotl(x,y)
 #else
-   #define stbi_lrot(x,y)  (((x) << (y)) | ((x) >> (32 - (y))))
+   #define stbi_lrot(x,y)  (((x) << (y)) | ((x) >> (-(y) & 31)))
 #endif
 
 #if defined(STBI_MALLOC) && defined(STBI_FREE) && (defined(STBI_REALLOC) || defined(STBI_REALLOC_SIZED))
@@ -748,9 +778,12 @@ static int stbi__sse2_available(void)
 
 #ifdef STBI_NEON
 #include <arm_neon.h>
-// assume GCC or Clang on ARM targets
+#ifdef _MSC_VER
+#define STBI_SIMD_ALIGN(type, name) __declspec(align(16)) type name
+#else
 #define STBI_SIMD_ALIGN(type, name) type name __attribute__((aligned(16)))
 #endif
+#endif
 
 #ifndef STBI_SIMD_ALIGN
 #define STBI_SIMD_ALIGN(type, name) type name
@@ -924,6 +957,7 @@ static int      stbi__gif_info(stbi__context *s, int *x, int *y, int *comp);
 static int      stbi__pnm_test(stbi__context *s);
 static void    *stbi__pnm_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static int      stbi__pnm_info(stbi__context *s, int *x, int *y, int *comp);
+static int      stbi__pnm_is16(stbi__context *s);
 #endif
 
 static
@@ -998,7 +1032,7 @@ static int stbi__mad3sizes_valid(int a, int b, int c, int add)
 }
 
 // returns 1 if "a*b*c*d + add" has no negative terms/factors and doesn't overflow
-#if !defined(STBI_NO_LINEAR) || !defined(STBI_NO_HDR)
+#if !defined(STBI_NO_LINEAR) || !defined(STBI_NO_HDR) || !defined(STBI_NO_PNM)
 static int stbi__mad4sizes_valid(int a, int b, int c, int d, int add)
 {
    return stbi__mul2sizes_valid(a, b) && stbi__mul2sizes_valid(a*b, c) &&
@@ -1021,7 +1055,7 @@ static void *stbi__malloc_mad3(int a, int b, int c, int add)
    return stbi__malloc(a*b*c + add);
 }
 
-#if !defined(STBI_NO_LINEAR) || !defined(STBI_NO_HDR)
+#if !defined(STBI_NO_LINEAR) || !defined(STBI_NO_HDR) || !defined(STBI_NO_PNM)
 static void *stbi__malloc_mad4(int a, int b, int c, int d, int add)
 {
    if (!stbi__mad4sizes_valid(a, b, c, d, add)) return NULL;
@@ -1087,9 +1121,8 @@ static void *stbi__load_main(stbi__context *s, int *x, int *y, int *comp, int re
    ri->channel_order = STBI_ORDER_RGB; // all current input & output are this, but this is here so we can add BGR order
    ri->num_channels = 0;
 
-   #ifndef STBI_NO_JPEG
-   if (stbi__jpeg_test(s)) return stbi__jpeg_load(s,x,y,comp,req_comp, ri);
-   #endif
+   // test the formats with a very explicit header first (at least a FOURCC
+   // or distinctive magic number first)
    #ifndef STBI_NO_PNG
    if (stbi__png_test(s))  return stbi__png_load(s,x,y,comp,req_comp, ri);
    #endif
@@ -1107,6 +1140,13 @@ static void *stbi__load_main(stbi__context *s, int *x, int *y, int *comp, int re
    #ifndef STBI_NO_PIC
    if (stbi__pic_test(s))  return stbi__pic_load(s,x,y,comp,req_comp, ri);
    #endif
+
+   // then the formats that can end up attempting to load with just 1 or 2
+   // bytes matching expectations; these are prone to false positives, so
+   // try them later
+   #ifndef STBI_NO_JPEG
+   if (stbi__jpeg_test(s)) return stbi__jpeg_load(s,x,y,comp,req_comp, ri);
+   #endif
    #ifndef STBI_NO_PNM
    if (stbi__pnm_test(s))  return stbi__pnm_load(s,x,y,comp,req_comp, ri);
    #endif
@@ -1262,12 +1302,12 @@ static void stbi__float_postprocess(float *result, int *x, int *y, int *comp, in
 
 #ifndef STBI_NO_STDIO
 
-#if defined(_MSC_VER) && defined(STBI_WINDOWS_UTF8)
+#if defined(_WIN32) && defined(STBI_WINDOWS_UTF8)
 STBI_EXTERN __declspec(dllimport) int __stdcall MultiByteToWideChar(unsigned int cp, unsigned long flags, const char *str, int cbmb, wchar_t *widestr, int cchwide);
 STBI_EXTERN __declspec(dllimport) int __stdcall WideCharToMultiByte(unsigned int cp, unsigned long flags, const wchar_t *widestr, int cchwide, char *str, int cbmb, const char *defchar, int *used_default);
 #endif
 
-#if defined(_MSC_VER) && defined(STBI_WINDOWS_UTF8)
+#if defined(_WIN32) && defined(STBI_WINDOWS_UTF8)
 STBIDEF int stbi_convert_wchar_to_utf8(char *buffer, size_t bufferlen, const wchar_t* input)
 {
 	return WideCharToMultiByte(65001 /* UTF8 */, 0, input, -1, buffer, (int) bufferlen, NULL, NULL);
@@ -1277,16 +1317,16 @@ STBIDEF int stbi_convert_wchar_to_utf8(char *buffer, size_t bufferlen, const wch
 static FILE *stbi__fopen(char const *filename, char const *mode)
 {
    FILE *f;
-#if defined(_MSC_VER) && defined(STBI_WINDOWS_UTF8)
+#if defined(_WIN32) && defined(STBI_WINDOWS_UTF8)
    wchar_t wMode[64];
    wchar_t wFilename[1024];
-	if (0 == MultiByteToWideChar(65001 /* UTF8 */, 0, filename, -1, wFilename, sizeof(wFilename)))
+	if (0 == MultiByteToWideChar(65001 /* UTF8 */, 0, filename, -1, wFilename, sizeof(wFilename)/sizeof(*wFilename)))
       return 0;
 
-	if (0 == MultiByteToWideChar(65001 /* UTF8 */, 0, mode, -1, wMode, sizeof(wMode)))
+	if (0 == MultiByteToWideChar(65001 /* UTF8 */, 0, mode, -1, wMode, sizeof(wMode)/sizeof(*wMode)))
       return 0;
 
-#if _MSC_VER >= 1400
+#if defined(_MSC_VER) && _MSC_VER >= 1400
 	if (0 != _wfopen_s(&f, wFilename, wMode))
 		f = 0;
 #else
@@ -1662,7 +1702,8 @@ static int stbi__get16le(stbi__context *s)
 static stbi__uint32 stbi__get32le(stbi__context *s)
 {
    stbi__uint32 z = stbi__get16le(s);
-   return z + (stbi__get16le(s) << 16);
+   z += (stbi__uint32)stbi__get16le(s) << 16;
+   return z;
 }
 #endif
 
@@ -2090,13 +2131,12 @@ stbi_inline static int stbi__extend_receive(stbi__jpeg *j, int n)
    int sgn;
    if (j->code_bits < n) stbi__grow_buffer_unsafe(j);
 
-   sgn = (stbi__int32)j->code_buffer >> 31; // sign bit is always in MSB
+   sgn = j->code_buffer >> 31; // sign bit always in MSB; 0 if MSB clear (positive), 1 if MSB set (negative)
    k = stbi_lrot(j->code_buffer, n);
-   if (n < 0 || n >= (int) (sizeof(stbi__bmask)/sizeof(*stbi__bmask))) return 0;
    j->code_buffer = k & ~stbi__bmask[n];
    k &= stbi__bmask[n];
    j->code_bits -= n;
-   return k + (stbi__jbias[n] & ~sgn);
+   return k + (stbi__jbias[n] & (sgn - 1));
 }
 
 // get some unsigned bits
@@ -2146,7 +2186,7 @@ static int stbi__jpeg_decode_block(stbi__jpeg *j, short data[64], stbi__huffman
 
    if (j->code_bits < 16) stbi__grow_buffer_unsafe(j);
    t = stbi__jpeg_huff_decode(j, hdc);
-   if (t < 0) return stbi__err("bad huffman code","Corrupt JPEG");
+   if (t < 0 || t > 15) return stbi__err("bad huffman code","Corrupt JPEG");
 
    // 0 all the ac values now so we can do it 32-bits at a time
    memset(data,0,64*sizeof(data[0]));
@@ -2203,12 +2243,12 @@ static int stbi__jpeg_decode_block_prog_dc(stbi__jpeg *j, short data[64], stbi__
       // first scan for DC coefficient, must be first
       memset(data,0,64*sizeof(data[0])); // 0 all the ac values now
       t = stbi__jpeg_huff_decode(j, hdc);
-      if (t == -1) return stbi__err("can't merge dc and ac", "Corrupt JPEG");
+      if (t < 0 || t > 15) return stbi__err("can't merge dc and ac", "Corrupt JPEG");
       diff = t ? stbi__extend_receive(j, t) : 0;
 
       dc = j->img_comp[b].dc_pred + diff;
       j->img_comp[b].dc_pred = dc;
-      data[0] = (short) (dc << j->succ_low);
+      data[0] = (short) (dc * (1 << j->succ_low));
    } else {
       // refinement scan for DC coefficient
       if (stbi__jpeg_get_bit(j))
@@ -2245,7 +2285,7 @@ static int stbi__jpeg_decode_block_prog_ac(stbi__jpeg *j, short data[64], stbi__
             j->code_buffer <<= s;
             j->code_bits -= s;
             zig = stbi__jpeg_dezigzag[k++];
-            data[zig] = (short) ((r >> 8) << shift);
+            data[zig] = (short) ((r >> 8) * (1 << shift));
          } else {
             int rs = stbi__jpeg_huff_decode(j, hac);
             if (rs < 0) return stbi__err("bad huffman code","Corrupt JPEG");
@@ -2263,7 +2303,7 @@ static int stbi__jpeg_decode_block_prog_ac(stbi__jpeg *j, short data[64], stbi__
             } else {
                k += r;
                zig = stbi__jpeg_dezigzag[k++];
-               data[zig] = (short) (stbi__extend_receive(j,s) << shift);
+               data[zig] = (short) (stbi__extend_receive(j,s) * (1 << shift));
             }
          }
       } while (k <= j->spec_end);
@@ -3227,6 +3267,13 @@ static int stbi__process_frame_header(stbi__jpeg *z, int scan)
       if (z->img_comp[i].v > v_max) v_max = z->img_comp[i].v;
    }
 
+   // check that plane subsampling factors are integer ratios; our resamplers can't deal with fractional ratios
+   // and I've never seen a non-corrupted JPEG file actually use them
+   for (i=0; i < s->img_n; ++i) {
+      if (h_max % z->img_comp[i].h != 0) return stbi__err("bad H","Corrupt JPEG");
+      if (v_max % z->img_comp[i].v != 0) return stbi__err("bad V","Corrupt JPEG");
+   }
+
    // compute interleaved mcu info
    z->img_h_max = h_max;
    z->img_v_max = v_max;
@@ -3782,6 +3829,10 @@ static stbi_uc *load_jpeg_image(stbi__jpeg *z, int *out_x, int *out_y, int *comp
    else
       decode_n = z->s->img_n;
 
+   // nothing to do if no components requested; check this now to avoid
+   // accessing uninitialized coutput[0] later
+   if (decode_n <= 0) { stbi__cleanup_jpeg(z); return NULL; }
+
    // resample and color-convert
    {
       int k;
@@ -3924,6 +3975,7 @@ static void *stbi__jpeg_load(stbi__context *s, int *x, int *y, int *comp, int re
 {
    unsigned char* result;
    stbi__jpeg* j = (stbi__jpeg*) stbi__malloc(sizeof(stbi__jpeg));
+   if (!j) return stbi__errpuc("outofmem", "Out of memory");
    STBI_NOTUSED(ri);
    j->s = s;
    stbi__setup_jpeg(j);
@@ -3936,6 +3988,7 @@ static int stbi__jpeg_test(stbi__context *s)
 {
    int r;
    stbi__jpeg* j = (stbi__jpeg*)stbi__malloc(sizeof(stbi__jpeg));
+   if (!j) return stbi__err("outofmem", "Out of memory");
    j->s = s;
    stbi__setup_jpeg(j);
    r = stbi__decode_jpeg_header(j, STBI__SCAN_type);
@@ -3960,6 +4013,7 @@ static int stbi__jpeg_info(stbi__context *s, int *x, int *y, int *comp)
 {
    int result;
    stbi__jpeg* j = (stbi__jpeg*) (stbi__malloc(sizeof(stbi__jpeg)));
+   if (!j) return stbi__err("outofmem", "Out of memory");
    j->s = s;
    result = stbi__jpeg_info_raw(j, x, y, comp);
    STBI_FREE(j);
@@ -3979,6 +4033,7 @@ static int stbi__jpeg_info(stbi__context *s, int *x, int *y, int *comp)
 // fast-way is faster to check than jpeg huffman, but slow way is slower
 #define STBI__ZFAST_BITS  9 // accelerate all cases in default tables
 #define STBI__ZFAST_MASK  ((1 << STBI__ZFAST_BITS) - 1)
+#define STBI__ZNSYMS 288 // number of symbols in literal/length alphabet
 
 // zlib-style huffman encoding
 // (jpegs packs from left, zlib from right, so can't share code)
@@ -3988,8 +4043,8 @@ typedef struct
    stbi__uint16 firstcode[16];
    int maxcode[17];
    stbi__uint16 firstsymbol[16];
-   stbi_uc  size[288];
-   stbi__uint16 value[288];
+   stbi_uc  size[STBI__ZNSYMS];
+   stbi__uint16 value[STBI__ZNSYMS];
 } stbi__zhuffman;
 
 stbi_inline static int stbi__bitreverse16(int n)
@@ -4120,7 +4175,7 @@ static int stbi__zhuffman_decode_slowpath(stbi__zbuf *a, stbi__zhuffman *z)
    if (s >= 16) return -1; // invalid code!
    // code size is s, so:
    b = (k >> (16-s)) - z->firstcode[s] + z->firstsymbol[s];
-   if (b >= sizeof (z->size)) return -1; // some data was corrupt somewhere!
+   if (b >= STBI__ZNSYMS) return -1; // some data was corrupt somewhere!
    if (z->size[b] != s) return -1;  // was originally an assert, but report failure instead.
    a->code_buffer >>= s;
    a->num_bits -= s;
@@ -4317,7 +4372,7 @@ static int stbi__parse_zlib_header(stbi__zbuf *a)
    return 1;
 }
 
-static const stbi_uc stbi__zdefault_length[288] =
+static const stbi_uc stbi__zdefault_length[STBI__ZNSYMS] =
 {
    8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
    8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
@@ -4363,7 +4418,7 @@ static int stbi__parse_zlib(stbi__zbuf *a, int parse_header)
       } else {
          if (type == 1) {
             // use fixed code lengths
-            if (!stbi__zbuild_huffman(&a->z_length  , stbi__zdefault_length  , 288)) return 0;
+            if (!stbi__zbuild_huffman(&a->z_length  , stbi__zdefault_length  , STBI__ZNSYMS)) return 0;
             if (!stbi__zbuild_huffman(&a->z_distance, stbi__zdefault_distance,  32)) return 0;
          } else {
             if (!stbi__compute_huffman_codes(a)) return 0;
@@ -4759,6 +4814,7 @@ static int stbi__create_png_image(stbi__png *a, stbi_uc *image_data, stbi__uint3
 
    // de-interlacing
    final = (stbi_uc *) stbi__malloc_mad3(a->s->img_x, a->s->img_y, out_bytes, 0);
+   if (!final) return stbi__err("outofmem", "Out of memory");
    for (p=0; p < 7; ++p) {
       int xorig[] = { 0,4,0,2,0,1,0 };
       int yorig[] = { 0,0,4,0,2,0,1 };
@@ -4879,19 +4935,46 @@ static int stbi__expand_png_palette(stbi__png *a, stbi_uc *palette, int len, int
    return 1;
 }
 
-static int stbi__unpremultiply_on_load = 0;
-static int stbi__de_iphone_flag = 0;
+static int stbi__unpremultiply_on_load_global = 0;
+static int stbi__de_iphone_flag_global = 0;
 
 STBIDEF void stbi_set_unpremultiply_on_load(int flag_true_if_should_unpremultiply)
 {
-   stbi__unpremultiply_on_load = flag_true_if_should_unpremultiply;
+   stbi__unpremultiply_on_load_global = flag_true_if_should_unpremultiply;
 }
 
 STBIDEF void stbi_convert_iphone_png_to_rgb(int flag_true_if_should_convert)
 {
-   stbi__de_iphone_flag = flag_true_if_should_convert;
+   stbi__de_iphone_flag_global = flag_true_if_should_convert;
+}
+
+#ifndef STBI_THREAD_LOCAL
+#define stbi__unpremultiply_on_load  stbi__unpremultiply_on_load_global
+#define stbi__de_iphone_flag  stbi__de_iphone_flag_global
+#else
+static STBI_THREAD_LOCAL int stbi__unpremultiply_on_load_local, stbi__unpremultiply_on_load_set;
+static STBI_THREAD_LOCAL int stbi__de_iphone_flag_local, stbi__de_iphone_flag_set;
+
+STBIDEF void stbi__unpremultiply_on_load_thread(int flag_true_if_should_unpremultiply)
+{
+   stbi__unpremultiply_on_load_local = flag_true_if_should_unpremultiply;
+   stbi__unpremultiply_on_load_set = 1;
+}
+
+STBIDEF void stbi_convert_iphone_png_to_rgb_thread(int flag_true_if_should_convert)
+{
+   stbi__de_iphone_flag_local = flag_true_if_should_convert;
+   stbi__de_iphone_flag_set = 1;
 }
 
+#define stbi__unpremultiply_on_load  (stbi__unpremultiply_on_load_set           \
+                                       ? stbi__unpremultiply_on_load_local      \
+                                       : stbi__unpremultiply_on_load_global)
+#define stbi__de_iphone_flag  (stbi__de_iphone_flag_set                         \
+                                ? stbi__de_iphone_flag_local                    \
+                                : stbi__de_iphone_flag_global)
+#endif // STBI_THREAD_LOCAL
+
 static void stbi__de_iphone(stbi__png *z)
 {
    stbi__context *s = z->s;
@@ -5272,6 +5355,32 @@ typedef struct
    int extra_read;
 } stbi__bmp_data;
 
+static int stbi__bmp_set_mask_defaults(stbi__bmp_data *info, int compress)
+{
+   // BI_BITFIELDS specifies masks explicitly, don't override
+   if (compress == 3)
+      return 1;
+
+   if (compress == 0) {
+      if (info->bpp == 16) {
+         info->mr = 31u << 10;
+         info->mg = 31u <<  5;
+         info->mb = 31u <<  0;
+      } else if (info->bpp == 32) {
+         info->mr = 0xffu << 16;
+         info->mg = 0xffu <<  8;
+         info->mb = 0xffu <<  0;
+         info->ma = 0xffu << 24;
+         info->all_a = 0; // if all_a is 0 at end, then we loaded alpha channel but it was all 0
+      } else {
+         // otherwise, use defaults, which is all-0
+         info->mr = info->mg = info->mb = info->ma = 0;
+      }
+      return 1;
+   }
+   return 0; // error
+}
+
 static void *stbi__bmp_parse_header(stbi__context *s, stbi__bmp_data *info)
 {
    int hsz;
@@ -5299,6 +5408,8 @@ static void *stbi__bmp_parse_header(stbi__context *s, stbi__bmp_data *info)
    if (hsz != 12) {
       int compress = stbi__get32le(s);
       if (compress == 1 || compress == 2) return stbi__errpuc("BMP RLE", "BMP type not supported: RLE");
+      if (compress >= 4) return stbi__errpuc("BMP JPEG/PNG", "BMP type not supported: unsupported compression"); // this includes PNG/JPEG modes
+      if (compress == 3 && info->bpp != 16 && info->bpp != 32) return stbi__errpuc("bad BMP", "bad BMP"); // bitfields requires 16 or 32 bits/pixel
       stbi__get32le(s); // discard sizeof
       stbi__get32le(s); // discard hres
       stbi__get32le(s); // discard vres
@@ -5313,17 +5424,7 @@ static void *stbi__bmp_parse_header(stbi__context *s, stbi__bmp_data *info)
          }
          if (info->bpp == 16 || info->bpp == 32) {
             if (compress == 0) {
-               if (info->bpp == 32) {
-                  info->mr = 0xffu << 16;
-                  info->mg = 0xffu <<  8;
-                  info->mb = 0xffu <<  0;
-                  info->ma = 0xffu << 24;
-                  info->all_a = 0; // if all_a is 0 at end, then we loaded alpha channel but it was all 0
-               } else {
-                  info->mr = 31u << 10;
-                  info->mg = 31u <<  5;
-                  info->mb = 31u <<  0;
-               }
+               stbi__bmp_set_mask_defaults(info, compress);
             } else if (compress == 3) {
                info->mr = stbi__get32le(s);
                info->mg = stbi__get32le(s);
@@ -5338,6 +5439,7 @@ static void *stbi__bmp_parse_header(stbi__context *s, stbi__bmp_data *info)
                return stbi__errpuc("bad BMP", "bad BMP");
          }
       } else {
+         // V4/V5 header
          int i;
          if (hsz != 108 && hsz != 124)
             return stbi__errpuc("bad BMP", "bad BMP");
@@ -5345,6 +5447,8 @@ static void *stbi__bmp_parse_header(stbi__context *s, stbi__bmp_data *info)
          info->mg = stbi__get32le(s);
          info->mb = stbi__get32le(s);
          info->ma = stbi__get32le(s);
+         if (compress != 3) // override mr/mg/mb unless in BI_BITFIELDS mode, as per docs
+            stbi__bmp_set_mask_defaults(info, compress);
          stbi__get32le(s); // discard color space
          for (i=0; i < 12; ++i)
             stbi__get32le(s); // discard color space parameters
@@ -5394,8 +5498,7 @@ static void *stbi__bmp_load(stbi__context *s, int *x, int *y, int *comp, int req
          psize = (info.offset - info.extra_read - info.hsz) >> 2;
    }
    if (psize == 0) {
-      STBI_ASSERT(info.offset == s->callback_already_read + (int) (s->img_buffer - s->img_buffer_original));
-      if (info.offset != s->callback_already_read + (s->img_buffer - s->buffer_start)) {
+      if (info.offset != s->callback_already_read + (s->img_buffer - s->img_buffer_original)) {
         return stbi__errpuc("bad offset", "Corrupt BMP");
       }
    }
@@ -6342,6 +6445,7 @@ static void *stbi__pic_load(stbi__context *s,int *px,int *py,int *comp,int req_c
 
    // intermediate buffer is RGBA
    result = (stbi_uc *) stbi__malloc_mad3(x, y, 4, 0);
+   if (!result) return stbi__errpuc("outofmem", "Out of memory");
    memset(result, 0xff, x*y*4);
 
    if (!stbi__pic_load_core(s,x,y,comp, result)) {
@@ -6457,6 +6561,7 @@ static int stbi__gif_header(stbi__context *s, stbi__gif *g, int *comp, int is_in
 static int stbi__gif_info_raw(stbi__context *s, int *x, int *y, int *comp)
 {
    stbi__gif* g = (stbi__gif*) stbi__malloc(sizeof(stbi__gif));
+   if (!g) return stbi__err("outofmem", "Out of memory");
    if (!stbi__gif_header(s, g, comp, 1)) {
       STBI_FREE(g);
       stbi__rewind( s );
@@ -6766,6 +6871,17 @@ static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, i
    }
 }
 
+static void *stbi__load_gif_main_outofmem(stbi__gif *g, stbi_uc *out, int **delays)
+{
+   STBI_FREE(g->out);
+   STBI_FREE(g->history);
+   STBI_FREE(g->background);
+
+   if (out) STBI_FREE(out);
+   if (delays && *delays) STBI_FREE(*delays);
+   return stbi__errpuc("outofmem", "Out of memory");
+}
+
 static void *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y, int *z, int *comp, int req_comp)
 {
    if (stbi__gif_test(s)) {
@@ -6777,6 +6893,10 @@ static void *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y,
       int stride;
       int out_size = 0;
       int delays_size = 0;
+
+      STBI_NOTUSED(out_size);
+      STBI_NOTUSED(delays_size);
+
       memset(&g, 0, sizeof(g));
       if (delays) {
          *delays = 0;
@@ -6794,26 +6914,29 @@ static void *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y,
 
             if (out) {
                void *tmp = (stbi_uc*) STBI_REALLOC_SIZED( out, out_size, layers * stride );
-               if (NULL == tmp) {
-                  STBI_FREE(g.out);
-                  STBI_FREE(g.history);
-                  STBI_FREE(g.background);
-                  return stbi__errpuc("outofmem", "Out of memory");
-               }
+               if (!tmp)
+                  return stbi__load_gif_main_outofmem(&g, out, delays);
                else {
                    out = (stbi_uc*) tmp;
                    out_size = layers * stride;
                }
 
                if (delays) {
-                  *delays = (int*) STBI_REALLOC_SIZED( *delays, delays_size, sizeof(int) * layers );
+                  int *new_delays = (int*) STBI_REALLOC_SIZED( *delays, delays_size, sizeof(int) * layers );
+                  if (!new_delays)
+                     return stbi__load_gif_main_outofmem(&g, out, delays);
+                  *delays = new_delays;
                   delays_size = layers * sizeof(int);
                }
             } else {
                out = (stbi_uc*)stbi__malloc( layers * stride );
+               if (!out)
+                  return stbi__load_gif_main_outofmem(&g, out, delays);
                out_size = layers * stride;
                if (delays) {
                   *delays = (int*) stbi__malloc( layers * sizeof(int) );
+                  if (!*delays)
+                     return stbi__load_gif_main_outofmem(&g, out, delays);
                   delays_size = layers * sizeof(int);
                }
             }
@@ -7138,9 +7261,10 @@ static int stbi__bmp_info(stbi__context *s, int *x, int *y, int *comp)
 
    info.all_a = 255;
    p = stbi__bmp_parse_header(s, &info);
-   stbi__rewind( s );
-   if (p == NULL)
+   if (p == NULL) {
+      stbi__rewind( s );
       return 0;
+   }
    if (x) *x = s->img_x;
    if (y) *y = s->img_y;
    if (comp) {
@@ -7206,8 +7330,8 @@ static int stbi__psd_is16(stbi__context *s)
        stbi__rewind( s );
        return 0;
    }
-   (void) stbi__get32be(s);
-   (void) stbi__get32be(s);
+   STBI_NOTUSED(stbi__get32be(s));
+   STBI_NOTUSED(stbi__get32be(s));
    depth = stbi__get16be(s);
    if (depth != 16) {
        stbi__rewind( s );
@@ -7286,7 +7410,6 @@ static int stbi__pic_info(stbi__context *s, int *x, int *y, int *comp)
 // Known limitations:
 //    Does not support comments in the header section
 //    Does not support ASCII image data (formats P2 and P3)
-//    Does not support 16-bit-per-channel
 
 #ifndef STBI_NO_PNM
 
@@ -7307,7 +7430,8 @@ static void *stbi__pnm_load(stbi__context *s, int *x, int *y, int *comp, int req
    stbi_uc *out;
    STBI_NOTUSED(ri);
 
-   if (!stbi__pnm_info(s, (int *)&s->img_x, (int *)&s->img_y, (int *)&s->img_n))
+   ri->bits_per_channel = stbi__pnm_info(s, (int *)&s->img_x, (int *)&s->img_y, (int *)&s->img_n);
+   if (ri->bits_per_channel == 0)
       return 0;
 
    if (s->img_y > STBI_MAX_DIMENSIONS) return stbi__errpuc("too large","Very large image (corrupt?)");
@@ -7317,12 +7441,12 @@ static void *stbi__pnm_load(stbi__context *s, int *x, int *y, int *comp, int req
    *y = s->img_y;
    if (comp) *comp = s->img_n;
 
-   if (!stbi__mad3sizes_valid(s->img_n, s->img_x, s->img_y, 0))
+   if (!stbi__mad4sizes_valid(s->img_n, s->img_x, s->img_y, ri->bits_per_channel / 8, 0))
       return stbi__errpuc("too large", "PNM too large");
 
-   out = (stbi_uc *) stbi__malloc_mad3(s->img_n, s->img_x, s->img_y, 0);
+   out = (stbi_uc *) stbi__malloc_mad4(s->img_n, s->img_x, s->img_y, ri->bits_per_channel / 8, 0);
    if (!out) return stbi__errpuc("outofmem", "Out of memory");
-   stbi__getn(s, out, s->img_n * s->img_x * s->img_y);
+   stbi__getn(s, out, s->img_n * s->img_x * s->img_y * (ri->bits_per_channel / 8));
 
    if (req_comp && req_comp != s->img_n) {
       out = stbi__convert_format(out, s->img_n, req_comp, s->img_x, s->img_y);
@@ -7398,11 +7522,19 @@ static int      stbi__pnm_info(stbi__context *s, int *x, int *y, int *comp)
    stbi__pnm_skip_whitespace(s, &c);
 
    maxv = stbi__pnm_getinteger(s, &c);  // read max value
-
-   if (maxv > 255)
-      return stbi__err("max value > 255", "PPM image not 8-bit");
+   if (maxv > 65535)
+      return stbi__err("max value > 65535", "PPM image supports only 8-bit and 16-bit images");
+   else if (maxv > 255)
+      return 16;
    else
-      return 1;
+      return 8;
+}
+
+static int stbi__pnm_is16(stbi__context *s)
+{
+   if (stbi__pnm_info(s, NULL, NULL, NULL) == 16)
+	   return 1;
+   return 0;
 }
 #endif
 
@@ -7458,6 +7590,9 @@ static int stbi__is_16_main(stbi__context *s)
    if (stbi__psd_is16(s))  return 1;
    #endif
 
+   #ifndef STBI_NO_PNM
+   if (stbi__pnm_is16(s))  return 1;
+   #endif
    return 0;
 }