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

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