Add become_root() capability to nfsv4_chmod()

[netatalk.git] / libatalk / util / unix.c

diff --git a/libatalk/util/unix.c b/libatalk/util/unix.c
index beb9ab5a3fe2958eb02e9ab7a7ea69d6d40277a6..e4cb21e8c12e95e828afb608430a73c8c034ebf8 100644 (file)
--- a/libatalk/util/unix.c
+++ b/libatalk/util/unix.c
@@ -1,5 +1,4 @@
 /*
-  $Id: unix.c,v 1.1 2010-01-05 13:48:47 franklahm Exp $
   Copyright (c) 2010 Frank Lahm <franklahm@gmail.com>
 
   This program is free software; you can redistribute it and/or modify
@@ -13,6 +12,11 @@
   GNU General Public License for more details.
 */
 
+/*!
+ * @file
+ * Netatalk utility functions
+ */
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif /* HAVE_CONFIG_H */
@@ -26,23 +30,244 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <dirent.h>
+#include <sys/time.h>
+#include <time.h>
 
 #include <atalk/adouble.h>
 #include <atalk/ea.h>
 #include <atalk/afp.h>
 #include <atalk/logger.h>
-#include <atalk/volume.h>
 #include <atalk/vfs.h>
 #include <atalk/util.h>
 #include <atalk/unix.h>
 
-extern const char *getcwdpath(void)
+/* close all FDs >= a specified value */
+static void closeall(int fd)
+{
+    int fdlimit = sysconf(_SC_OPEN_MAX);
+
+    while (fd < fdlimit)
+        close(fd++);
+}
+
+/*!
+ * Daemonize
+ *
+ * Fork, exit parent, setsid(), optionally chdir("/"), optionally close all fds
+ *
+ * returns -1 on failure, but you can't do much except exit in that case
+ * since we may already have forked
+ */
+int daemonize(int nochdir, int noclose)
+{
+    switch (fork()) {
+    case 0:
+        break;
+    case -1:
+        return -1;
+    default:
+        _exit(0);
+    }
+
+    if (setsid() < 0)
+        return -1;
+
+    switch (fork()) {
+    case 0: 
+        break;
+    case -1:
+        return -1;
+    default:
+        _exit(0);
+    }
+
+    if (!nochdir)
+        chdir("/");
+
+    if (!noclose) {
+        closeall(0);
+        open("/dev/null",O_RDWR);
+        dup(0);
+        dup(0);
+    }
+
+    return 0;
+}
+
+static uid_t saved_uid = -1;
+
+void become_root(void)
+{
+    saved_uid = geteuid();
+    if (seteuid(0) != 0)
+        AFP_PANIC("Can't seteuid(0)");
+}
+
+void unbecome_root(void)
+{
+    if (saved_uid == -1 || seteuid(saved_uid) < 0)
+        AFP_PANIC("Can't seteuid back");
+    saved_uid = -1;
+}
+
+/*!
+ * @brief get cwd in static buffer
+ *
+ * @returns pointer to path or pointer to error messages on error
+ */
+const char *getcwdpath(void)
 {
     static char cwd[MAXPATHLEN + 1];
     char *p;
 
-    if ((p = getcwd(&cwd, MAXPATHLEN)) != NULL)
+    if ((p = getcwd(cwd, MAXPATHLEN)) != NULL)
         return p;
     else
         return strerror(errno);
 }
+
+/*!
+ * @brief Request absolute path
+ *
+ * @returns Absolute filesystem path to object
+ */
+const char *fullpathname(const char *name)
+{
+    static char wd[MAXPATHLEN + 1];
+
+    if (name[0] == '/')
+        return name;
+
+    if (getcwd(wd , MAXPATHLEN)) {
+        strlcat(wd, "/", MAXPATHLEN);
+        strlcat(wd, name, MAXPATHLEN);
+    } else {
+        strlcpy(wd, name, MAXPATHLEN);
+    }
+
+    return wd;
+}
+
+/*!
+ * Takes a buffer with a path, strips slashs, returns basename
+ *
+ * @param p (rw) path
+ *        path may be
+ *          "[/][dir/[...]]file"
+ *        or
+ *          "[/][dir/[...]]dir/[/]"
+ *        Result is "file" or "dir" 
+ *
+ * @returns pointer to basename in path buffer, buffer is possibly modified
+ */
+char *stripped_slashes_basename(char *p)
+{
+    int i = strlen(p) - 1;
+    while (i > 0 && p[i] == '/')
+        p[i--] = 0;
+    return (strrchr(p, '/') ? strrchr(p, '/') + 1 : p);
+}
+
+/*!
+ * @brief symlink safe chdir replacement
+ *
+ * Only chdirs to dir if it doesn't contain symlinks.
+ *
+ * @returns 1 if a path element is a symlink, 0 otherwise, -1 on syserror
+ */
+int lchdir(const char *dir)
+{
+    char buf[MAXPATHLEN+1];
+    char cwd[MAXPATHLEN+1];
+    char *test;
+    int  i;
+
+    /*
+     dir is a canonical path (without "../" "./" "//" )
+     but may end with a / 
+    */
+    *cwd = 0;
+    if (*dir != '/') {
+        if (getcwd(cwd, MAXPATHLEN) == NULL)
+            return -1;
+    }
+    if (chdir(dir) != 0)
+        return -1;
+
+    /* 
+     * Cases:
+     * chdir request   | realpath result | ret
+     * (after getwcwd) |                 |
+     * =======================================
+     * /a/b/.          | /a/b            | 0
+     * /a/b/.          | /c              | 1
+     * /a/b/.          | /c/d/e/f        | 1
+     */
+    if (getcwd(buf, MAXPATHLEN) == NULL)
+        return 1;
+
+    i = 0;
+    if (*cwd) {
+        /* relative path requested, 
+         * Same directory?
+        */
+        for (; cwd[i]; i++) {
+            if (buf[i] != cwd[i])
+                return 1;
+        }
+        if (buf[i]) {
+            if (buf[i] != '/')
+                return 1;
+            i++;
+        }                    
+    }
+
+    test = &buf[i];    
+    for (i = 0; test[i]; i++) {
+        if (test[i] != dir[i]) {
+            return 1;
+        }
+    }
+    /* trailing '/' ? */
+    if (!dir[i])
+        return 0;
+
+    if (dir[i] != '/')
+        return 1;
+
+    i++;
+    if (dir[i])
+        return 1;
+
+    return 0;
+}
+
+/*!
+ * Store n random bytes an buf
+ */
+void randombytes(void *buf, int n)
+{
+    char *p = (char *)buf;
+    int fd, i;
+    struct timeval tv;
+
+    if ((fd = open("/dev/urandom", O_RDONLY)) != -1) {
+        /* generate from /dev/urandom */
+        if (read(fd, buf, n) != n) {
+            close(fd);
+            fd = -1;
+        } else {
+            close(fd);
+            /* fd now != -1, so srandom wont be called below */
+        }
+    }
+
+    if (fd == -1) {
+        gettimeofday(&tv, NULL);
+        srandom((unsigned int)tv.tv_usec);
+        for (i=0 ; i < n ; i++)
+            p[i] = random() & 0xFF;
+    }
+
+    return;
+}