quickjs-tart

quickjs-based runtime for wallet-core logic
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CURLOPT_IOCTLFUNCTION.md (2585B)

      1 ---
      2 c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
      3 SPDX-License-Identifier: curl
      4 Title: CURLOPT_IOCTLFUNCTION
      5 Section: 3
      6 Source: libcurl
      7 Protocol:
      8   - All
      9 See-also:
     10   - CURLOPT_IOCTLDATA (3)
     11   - CURLOPT_SEEKFUNCTION (3)
     12 Added-in: 7.12.3
     13 ---
     14 
     15 # NAME
     16 
     17 CURLOPT_IOCTLFUNCTION - callback for I/O operations
     18 
     19 # SYNOPSIS
     20 
     21 ~~~c
     22 #include <curl/curl.h>
     23 
     24 typedef enum {
     25   CURLIOE_OK,            /* I/O operation successful */
     26   CURLIOE_UNKNOWNCMD,    /* command was unknown to callback */
     27   CURLIOE_FAILRESTART,   /* failed to restart the read */
     28   CURLIOE_LAST           /* never use */
     29 } curlioerr;
     30 
     31 typedef enum  {
     32   CURLIOCMD_NOP,         /* no operation */
     33   CURLIOCMD_RESTARTREAD, /* restart the read stream from start */
     34   CURLIOCMD_LAST         /* never use */
     35 } curliocmd;
     36 
     37 curlioerr ioctl_callback(CURL *handle, int cmd, void *clientp);
     38 
     39 CURLcode curl_easy_setopt(CURL *handle, CURLOPT_IOCTLFUNCTION, ioctl_callback);
     40 ~~~
     41 
     42 # DESCRIPTION
     43 
     44 Pass a pointer to your callback function, which should match the prototype
     45 shown above.
     46 
     47 This callback function gets called by libcurl when something special
     48 I/O-related needs to be done that the library cannot do by itself. For now,
     49 rewinding the read data stream is the only action it can request. The
     50 rewinding of the read data stream may be necessary when doing an HTTP PUT or
     51 POST with a multi-pass authentication method.
     52 
     53 The callback MUST return *CURLIOE_UNKNOWNCMD* if the input *cmd* is
     54 not *CURLIOCMD_RESTARTREAD*.
     55 
     56 The *clientp* argument to the callback is set with the
     57 CURLOPT_IOCTLDATA(3) option.
     58 
     59 **This option is deprecated**. Do not use it. Use CURLOPT_SEEKFUNCTION(3)
     60 instead to provide seeking. If CURLOPT_SEEKFUNCTION(3) is set, this
     61 parameter is ignored when seeking.
     62 
     63 # DEFAULT
     64 
     65 NULL
     66 
     67 # %PROTOCOLS%
     68 
     69 # EXAMPLE
     70 
     71 ~~~c
     72 #include <unistd.h> /* for lseek */
     73 
     74 struct data {
     75   int fd; /* our file descriptor */
     76 };
     77 
     78 static curlioerr ioctl_callback(CURL *handle, int cmd, void *clientp)
     79 {
     80   struct data *io = (struct data *)clientp;
     81   if(cmd == CURLIOCMD_RESTARTREAD) {
     82     lseek(io->fd, 0, SEEK_SET);
     83     return CURLIOE_OK;
     84   }
     85   return CURLIOE_UNKNOWNCMD;
     86 }
     87 int main(void)
     88 {
     89   struct data ioctl_data;
     90   CURL *curl = curl_easy_init();
     91   if(curl) {
     92     curl_easy_setopt(curl, CURLOPT_IOCTLFUNCTION, ioctl_callback);
     93     curl_easy_setopt(curl, CURLOPT_IOCTLDATA, &ioctl_data);
     94   }
     95 }
     96 ~~~
     97 
     98 # DEPRECATED
     99 
    100 Deprecated since 7.18.0.
    101 
    102 # %AVAILABILITY%
    103 
    104 # RETURN VALUE
    105 
    106 curl_easy_setopt(3) returns a CURLcode indicating success or error.
    107 
    108 CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
    109 libcurl-errors(3).