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