diplodocus.org Git - nmh/blob - sbr/m_mktemp.c

   1 /*
   2  * m_mktemp.c -- Construct a temporary file.
   3  *
   4  * $Id$
   5  *
   6  * This code is Copyright (c) 2010, by the authors of nmh.  See the
   7  * COPYRIGHT file in the root directory of the nmh distribution for
   8  * complete copyright information.
   9  */
  10
  11 #include <errno.h>
  12 #include <h/mh.h>
  13
  14 static char *get_temp_dir();
  15
  16 /*  Create a temporary file.  If pfx_in is null, the temporary file
  17  *  will be created in the temporary directory (more on that later).
  18  *  If pfx_in is not null, then the temporary file location will be
  19  *  defined by the value pfx_in.
  20  *
  21  *  The file created will be at the pathname specified appended with
  22  *  6 random (we hope :) characters.
  23  *
  24  *  The return value will be the pathname to the file created.
  25  *
  26  *  CAUTION: The return pointer references static data.  If
  27  *  you need to modify, or save, the return string, make a copy of it
  28  *  first.
  29  *
  30  *  When pfx_in is null, the temporary directory is determined as
  31  *  follows, in order:
  32  *
  33  *    MHTMPDIR envvar
  34  *    TMPDIR envvar
  35  *    TMP envvar
  36  *    User's mail directory.
  37  *
  38  *  NOTE: One will probably use m_mktemp2() instead of this function.
  39  *  For example, if you want to create a temp file in the defined
  40  *  temporary directory, but with a custom basename prefix, do
  41  *  something like the following:
  42  *
  43  *    char *tmp_pathname = m_mktemp2(NULL, "mypre", ...);
  44  */
  45 char *
  46 m_mktemp (
  47     const char *pfx_in,   /* Pathname prefix for temporary file. */
  48     int *fd_ret,          /* (return,optional) File descriptor to temp file. */
  49     FILE **fp_ret         /* (return,optional) FILE pointer to temp file. */
  50 )
  51 {
  52     static char tmpfil[BUFSIZ];
  53     int fd = -1;
  54     int keep_open = 0;
  55     mode_t oldmode = umask(077);
  56
  57     if (pfx_in == NULL) {
  58         snprintf(tmpfil, sizeof(tmpfil), "%s/nmhXXXXXX", get_temp_dir());
  59     } else {
  60         snprintf(tmpfil, sizeof(tmpfil), "%sXXXXXX", pfx_in);
  61     }
  62
  63     fd = mkstemp(tmpfil);
  64     if (fd < 0) {
  65         umask(oldmode);
  66         return NULL;
  67     }
  68     if (fd_ret != NULL) {
  69         *fd_ret = fd;
  70         keep_open = 1;
  71     }
  72     if (fp_ret != NULL) {
  73         FILE *fp = fdopen(fd, "w+");
  74         if (fp == NULL) {
  75             int olderr = errno;
  76             unlink(tmpfil);
  77             close(fd);
  78             errno = olderr;
  79             umask(oldmode);
  80             return NULL;
  81         }
  82         *fp_ret = fp;
  83         keep_open = 1;
  84     }
  85     if (!keep_open) {
  86         close(fd);
  87     }
  88     umask(oldmode);
  89     return tmpfil;
  90 }
  91
  92 /* This version allows one to specify the directory the temp file should
  93  * by created based on a given pathname.  Although m_mktemp() technically
  94  * supports this, this version is when the directory is defined by
  95  * a separate variable from the prefix, eliminating the caller from having
  96  * to do string manipulation to generate the desired. pathname prefix.
  97  *
  98  * The pfx_in parameter specifies a basename prefix for the file.  If dir_in
  99  * is NULL, then the defined temporary directory (see comments to m_mktemp()
 100  * above) is used to create the temp file.
 101  */
 102 char *
 103 m_mktemp2 (
 104     const char *dir_in,   /* Directory to place temp file. */
 105     const char *pfx_in,   /* Basename prefix for temp file. */
 106     int *fd_ret,          /* (return,optional) File descriptor to temp file. */
 107     FILE **fp_ret         /* (return,optional) FILE pointer to temp file. */
 108 )
 109 {
 110     static char buffer[BUFSIZ];
 111     char *cp;
 112     int n;
 113
 114     if (dir_in == NULL) {
 115         if (pfx_in == NULL) {
 116             return m_mktemp(NULL, fd_ret, fp_ret);
 117         }
 118         snprintf(buffer, sizeof(buffer), "%s/%s", get_temp_dir(), pfx_in);
 119         return m_mktemp(buffer, fd_ret, fp_ret);
 120     }
 121
 122     if ((cp = r1bindex ((char *)dir_in, '/')) == dir_in) {
 123         /* No directory component */
 124         return m_mktemp(pfx_in, fd_ret, fp_ret);
 125     }
 126     n = (int)(cp-dir_in-1); /* Length of dir component */
 127     snprintf(buffer, sizeof(buffer), "%.*s%s", n, dir_in, pfx_in);
 128     return m_mktemp(buffer, fd_ret, fp_ret);
 129 }
 130
 131
 132 static char *
 133 get_temp_dir()
 134 {
 135     // Ignore envvars if we are setuid
 136     if ((getuid()==geteuid()) && (getgid()==getegid())) {
 137         char *tmpdir = NULL;
 138         tmpdir = getenv("MHTMPDIR");
 139         if (tmpdir != NULL && *tmpdir != '\0') return tmpdir;
 140
 141         tmpdir = getenv("TMPDIR");
 142         if (tmpdir != NULL && *tmpdir != '\0') return tmpdir;
 143
 144         tmpdir = getenv("TMP");
 145         if (tmpdir != NULL && *tmpdir != '\0') return tmpdir;
 146     }
 147     return m_maildir("");
 148 }