CURLOPT_HEADERDATA.3 2.6 KB

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  25. .TH CURLOPT_HEADERDATA 3 "May 17, 2022" "libcurl 7.85.0" "curl_easy_setopt options"
  26. .SH NAME
  27. CURLOPT_HEADERDATA \- pointer to pass to header callback
  28. .SH SYNOPSIS
  29. .nf
  30. #include <curl/curl.h>
  31. CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HEADERDATA, void *pointer);
  32. .fi
  33. .SH DESCRIPTION
  34. Pass a \fIpointer\fP to be used to write the header part of the received data
  35. to.
  36. If \fICURLOPT_WRITEFUNCTION(3)\fP or \fICURLOPT_HEADERFUNCTION(3)\fP is used,
  37. \fIpointer\fP will be passed in to the respective callback.
  38. If neither of those options are set, \fIpointer\fP must be a valid FILE * and
  39. it will be used by a plain fwrite() to write headers to.
  40. .SH DEFAULT
  41. NULL
  42. .SH PROTOCOLS
  43. All
  44. .SH EXAMPLE
  45. .nf
  46. struct my_info {
  47. int shoesize;
  48. char *secret;
  49. };
  50. static size_t header_callback(char *buffer, size_t size,
  51. size_t nitems, void *userdata)
  52. {
  53. struct my_info *i = (struct my_info *)userdata;
  54. /* now this callback can access the my_info struct */
  55. return nitems * size;
  56. }
  57. CURL *curl = curl_easy_init();
  58. if(curl) {
  59. struct my_info my = { 10, "the cookies are in the cupboard" };
  60. curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
  61. curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, header_callback);
  62. /* pass in custom data to the callback */
  63. curl_easy_setopt(curl, CURLOPT_HEADERDATA, &my);
  64. curl_easy_perform(curl);
  65. }
  66. .fi
  67. .SH AVAILABILITY
  68. Always
  69. .SH RETURN VALUE
  70. Returns CURLE_OK
  71. .SH "SEE ALSO"
  72. .BR CURLOPT_HEADERFUNCTION "(3), " CURLOPT_WRITEFUNCTION "(3), "