memstream.h

   1 /*
   2  * Copyright 2012 (C) Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * SPDX-License-Identifier: MIT
   5  *
   6  */
   7
   8 #ifndef _LTTNG_CTL_MEMSTREAM_H
   9 #define _LTTNG_CTL_MEMSTREAM_H
  10
  11 #ifdef LTTNG_HAVE_FMEMOPEN
  12 #include <stdio.h>
  13
  14 static inline
  15 FILE *lttng_fmemopen(void *buf, size_t size, const char *mode)
  16 {
  17         return fmemopen(buf, size, mode);
  18 }
  19
  20 #else /* LTTNG_HAVE_FMEMOPEN */
  21
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24 #include <common/error.h>
  25
  26 /*
  27  * Fallback for systems which don't have fmemopen. Copy buffer to a
  28  * temporary file, and use that file as FILE * input.
  29  */
  30 static inline
  31 FILE *lttng_fmemopen(void *buf, size_t size, const char *mode)
  32 {
  33         char tmpname[PATH_MAX];
  34         size_t len;
  35         FILE *fp;
  36         int ret;
  37
  38         /*
  39          * Support reading only.
  40          */
  41         if (strcmp(mode, "rb") != 0) {
  42                 return NULL;
  43         }
  44         strncpy(tmpname, "/tmp/lttng-tmp-XXXXXX", PATH_MAX);
  45         ret = mkstemp(tmpname);
  46         if (ret < 0) {
  47                 return NULL;
  48         }
  49         /*
  50          * We need to write to the file.
  51          */
  52         fp = fdopen(ret, "w+");
  53         if (!fp) {
  54                 goto error_unlink;
  55         }
  56         /* Copy the entire buffer to the file */
  57         len = fwrite(buf, sizeof(char), size, fp);
  58         if (len != size) {
  59                 goto error_close;
  60         }
  61         ret = fseek(fp, 0L, SEEK_SET);
  62         if (ret < 0) {
  63                 PERROR("fseek");
  64                 goto error_close;
  65         }
  66         /* We keep the handle open, but can unlink the file on the VFS. */
  67         ret = unlink(tmpname);
  68         if (ret < 0) {
  69                 PERROR("unlink");
  70         }
  71         return fp;
  72
  73 error_close:
  74         ret = fclose(fp);
  75         if (ret < 0) {
  76                 PERROR("close");
  77         }
  78 error_unlink:
  79         ret = unlink(tmpname);
  80         if (ret < 0) {
  81                 PERROR("unlink");
  82         }
  83         return NULL;
  84 }
  85
  86 #endif /* LTTNG_HAVE_FMEMOPEN */
  87
  88 #endif /* _LTTNG_CTL_MEMSTREAM_H */