* Bug #15213, #18635: The use of the insecure m_scratch() and

[mmh] / sbr / m_mktemp.c

diff --git a/sbr/m_mktemp.c b/sbr/m_mktemp.c
new file mode 100644 (file)
index 0000000..2229036
--- /dev/null
+++ b/sbr/m_mktemp.c
@@ -0,0 +1,147 @@
+/*
+ * m_mktemp.c -- Construct a temporary file.
+ *
+ * $Id$
+ *
+ * This code is Copyright (c) 2010, by the authors of nmh.  See the
+ * COPYRIGHT file in the root directory of the nmh distribution for
+ * complete copyright information.
+ */
+
+#include <errno.h>
+#include <h/mh.h>
+
+static char *get_temp_dir();
+
+/*  Create a temporary file.  If pfx_in is null, the temporary file
+ *  will be created in the temporary directory (more on that later).
+ *  If pfx_in is not null, then the temporary file location will be
+ *  defined by the value pfx_in.
+ *
+ *  The file created will be at the pathname specified appended with
+ *  6 random (we hope :) characters.
+ *
+ *  The return value will be the pathname to the file created.
+ *
+ *  CAUTION: The return pointer references static data.  If
+ *  you need to modify, or save, the return string, make a copy of it
+ *  first.
+ *
+ *  When pfx_in is null, the temporary directory is determined as
+ *  follows, in order:
+ *  
+ *    MHTMPDIR envvar
+ *    TMPDIR envvar
+ *    TMP envvar
+ *    User's mail directory.
+ *
+ *  NOTE: One will probably use m_mktemp2() instead of this function.
+ *  For example, if you want to create a temp file in the defined
+ *  temporary directory, but with a custom basename prefix, do
+ *  something like the following:
+ *
+ *    char *tmp_pathname = m_mktemp2(NULL, "mypre", ...);
+ */
+char *
+m_mktemp (
+    const char *pfx_in,   /* Pathname prefix for temporary file. */
+    int *fd_ret,          /* (return,optional) File descriptor to temp file. */
+    FILE **fp_ret         /* (return,optional) FILE pointer to temp file. */
+)
+{
+    static char tmpfil[BUFSIZ];
+    int fd = -1;
+    int keep_open = 0;
+    mode_t oldmode = umask(077);
+
+    if (pfx_in == NULL) {
+        snprintf(tmpfil, sizeof(tmpfil), "%s/nmhXXXXXX", get_temp_dir());
+    } else {
+        snprintf(tmpfil, sizeof(tmpfil), "%sXXXXXX", pfx_in);
+    }
+
+    fd = mkstemp(tmpfil);
+    if (fd < 0) {
+        umask(oldmode);
+        return NULL;
+    }
+    if (fd_ret != NULL) {
+        *fd_ret = fd;
+        keep_open = 1;
+    }
+    if (fp_ret != NULL) {
+        FILE *fp = fdopen(fd, "w+");
+        if (fp == NULL) {
+            int olderr = errno;
+            unlink(tmpfil);
+            close(fd);
+            errno = olderr;
+            umask(oldmode);
+            return NULL;
+        }
+        *fp_ret = fp;
+        keep_open = 1;
+    }
+    if (!keep_open) {
+        close(fd);
+    }
+    umask(oldmode);
+    return tmpfil;
+}
+
+/* This version allows one to specify the directory the temp file should
+ * by created based on a given pathname.  Although m_mktemp() technically
+ * supports this, this version is when the directory is defined by
+ * a separate variable from the prefix, eliminating the caller from having
+ * to do string manipulation to generate the desired. pathname prefix.
+ *
+ * The pfx_in parameter specifies a basename prefix for the file.  If dir_in
+ * is NULL, then the defined temporary directory (see comments to m_mktemp()
+ * above) is used to create the temp file.
+ */
+char *
+m_mktemp2 (
+    const char *dir_in,   /* Directory to place temp file. */
+    const char *pfx_in,   /* Basename prefix for temp file. */
+    int *fd_ret,          /* (return,optional) File descriptor to temp file. */
+    FILE **fp_ret         /* (return,optional) FILE pointer to temp file. */
+)
+{
+    static char buffer[BUFSIZ];
+    char *cp;
+
+    if (dir_in == NULL) {
+        if (pfx_in == NULL) {
+            return m_mktemp(NULL, fd_ret, fp_ret);
+        }
+        snprintf(buffer, sizeof(buffer), "%s/%s", get_temp_dir(), pfx_in);
+        return m_mktemp(buffer, fd_ret, fp_ret);
+    }
+
+    if ((cp = r1bindex ((char *)dir_in, '/')) == dir_in) {
+        /* No directory component */
+        return m_mktemp(pfx_in, fd_ret, fp_ret);
+    }
+    int n = (int)(cp-dir_in-1); /* Length of dir component */
+    snprintf(buffer, sizeof(buffer), "%.*s%s", n, dir_in, pfx_in);
+    return m_mktemp(buffer, fd_ret, fp_ret);
+}
+
+
+static char *
+get_temp_dir()
+{
+    // Ignore envvars if we are setuid
+    if ((getuid()==geteuid()) && (getgid()==getegid())) {
+        char *tmpdir = NULL;
+        tmpdir = getenv("MHTMPDIR");
+        if (tmpdir != NULL && *tmpdir != '\0') return tmpdir;
+
+        tmpdir = getenv("TMPDIR");
+        if (tmpdir != NULL && *tmpdir != '\0') return tmpdir;
+
+        tmpdir = getenv("TMP");
+        if (tmpdir != NULL && *tmpdir != '\0') return tmpdir;
+    }
+    return m_maildir("");
+}