src/lib/lttng-ctl/filter/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
  25 /*
  26  * Fallback for systems which don't have fmemopen. Copy buffer to a
  27  * temporary file, and use that file as FILE * input.
  28  */
  29 static inline
  30 FILE *lttng_fmemopen(void *buf, size_t size, const char *mode)
  31 {
  32         char tmpname[PATH_MAX];
  33         size_t len;
  34         FILE *fp;
  35         int ret;
  36
  37         /*
  38          * Support reading only.
  39          */
  40         if (strcmp(mode, "rb") != 0) {
  41                 return NULL;
  42         }
  43         strncpy(tmpname, "/tmp/lttng-tmp-XXXXXX", PATH_MAX);
  44         ret = mkstemp(tmpname);
  45         if (ret < 0) {
  46                 return NULL;
  47         }
  48         /*
  49          * We need to write to the file.
  50          */
  51         fp = fdopen(ret, "w+");
  52         if (!fp) {
  53                 goto error_unlink;
  54         }
  55         /* Copy the entire buffer to the file */
  56         len = fwrite(buf, sizeof(char), size, fp);
  57         if (len != size) {
  58                 goto error_close;
  59         }
  60         ret = fseek(fp, 0L, SEEK_SET);
  61         if (ret < 0) {
  62                 PERROR("fseek");
  63                 goto error_close;
  64         }
  65         /* We keep the handle open, but can unlink the file on the VFS. */
  66         ret = unlink(tmpname);
  67         if (ret < 0) {
  68                 PERROR("unlink");
  69         }
  70         return fp;
  71
  72 error_close:
  73         ret = fclose(fp);
  74         if (ret < 0) {
  75                 PERROR("close");
  76         }
  77 error_unlink:
  78         ret = unlink(tmpname);
  79         if (ret < 0) {
  80                 PERROR("unlink");
  81         }
  82         return NULL;
  83 }
  84
  85 #endif /* LTTNG_HAVE_FMEMOPEN */
  86
  87 #endif /* _LTTNG_CTL_MEMSTREAM_H */