binman: Tidy up some docs and comments

[u-boot] / tools / env / fw_env.c

diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index f3bfee407d115b055ae511cfcd7a9dac4037086b..4b2caf696041b3fc428691db2ca12269001b8a78 100644 (file)
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -1,11 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * (C) Copyright 2000-2010
  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
  *
  * (C) Copyright 2008
  * Guennadi Liakhovetski, DENX Software Engineering, lg@denx.de.
- *
- * SPDX-License-Identifier:    GPL-2.0+
  */
 
 #define _GNU_SOURCE
@@ -14,6 +13,7 @@
 #include <errno.h>
 #include <env_flags.h>
 #include <fcntl.h>
+#include <libgen.h>
 #include <linux/fs.h>
 #include <linux/stringify.h>
 #include <ctype.h>
@@ -1225,65 +1225,149 @@ static int flash_read(int fd)
        return 0;
 }
 
-static int flash_io(int mode)
+static int flash_open_tempfile(const char **dname, const char **target_temp)
 {
-       int fd_current, fd_target, rc, dev_target;
+       char *dup_name = strdup(DEVNAME(dev_current));
+       char *temp_name = NULL;
+       int rc = -1;
 
-       /* dev_current: fd_current, erase_current */
-       fd_current = open(DEVNAME(dev_current), mode);
-       if (fd_current < 0) {
-               fprintf(stderr,
-                       "Can't open %s: %s\n",
-                       DEVNAME(dev_current), strerror(errno));
+       if (!dup_name)
                return -1;
+
+       *dname = dirname(dup_name);
+       if (!*dname)
+               goto err;
+
+       rc = asprintf(&temp_name, "%s/XXXXXX", *dname);
+       if (rc == -1)
+               goto err;
+
+       rc = mkstemp(temp_name);
+       if (rc == -1) {
+               /* fall back to in place write */
+               fprintf(stderr,
+                       "Can't create %s: %s\n", temp_name, strerror(errno));
+               free(temp_name);
+       } else {
+               *target_temp = temp_name;
+               /* deliberately leak dup_name as dname /might/ point into
+                * it and we need it for our caller
+                */
+               dup_name = NULL;
        }
 
-       if (mode == O_RDWR) {
-               if (have_redund_env) {
-                       /* switch to next partition for writing */
-                       dev_target = !dev_current;
-                       /* dev_target: fd_target, erase_target */
-                       fd_target = open(DEVNAME(dev_target), mode);
-                       if (fd_target < 0) {
-                               fprintf(stderr,
-                                       "Can't open %s: %s\n",
-                                       DEVNAME(dev_target), strerror(errno));
-                               rc = -1;
-                               goto exit;
-                       }
-               } else {
-                       dev_target = dev_current;
-                       fd_target = fd_current;
+err:
+       if (dup_name)
+               free(dup_name);
+
+       return rc;
+}
+
+static int flash_io_write(int fd_current)
+{
+       int fd_target = -1, rc, dev_target;
+       const char *dname, *target_temp = NULL;
+
+       if (have_redund_env) {
+               /* switch to next partition for writing */
+               dev_target = !dev_current;
+               /* dev_target: fd_target, erase_target */
+               fd_target = open(DEVNAME(dev_target), O_RDWR);
+               if (fd_target < 0) {
+                       fprintf(stderr,
+                               "Can't open %s: %s\n",
+                               DEVNAME(dev_target), strerror(errno));
+                       rc = -1;
+                       goto exit;
                }
+       } else {
+               struct stat sb;
+
+               if (fstat(fd_current, &sb) == 0 && S_ISREG(sb.st_mode)) {
+                       /* if any part of flash_open_tempfile() fails we fall
+                        * back to in-place writes
+                        */
+                       fd_target = flash_open_tempfile(&dname, &target_temp);
+               }
+               dev_target = dev_current;
+               if (fd_target == -1)
+                       fd_target = fd_current;
+       }
 
-               rc = flash_write(fd_current, fd_target, dev_target);
+       rc = flash_write(fd_current, fd_target, dev_target);
 
-               if (fsync(fd_current) && !(errno == EINVAL || errno == EROFS)) {
+       if (fsync(fd_current) && !(errno == EINVAL || errno == EROFS)) {
+               fprintf(stderr,
+                       "fsync failed on %s: %s\n",
+                       DEVNAME(dev_current), strerror(errno));
+       }
+
+       if (fd_current != fd_target) {
+               if (fsync(fd_target) &&
+                   !(errno == EINVAL || errno == EROFS)) {
                        fprintf(stderr,
                                "fsync failed on %s: %s\n",
                                DEVNAME(dev_current), strerror(errno));
                }
 
-               if (have_redund_env) {
-                       if (fsync(fd_target) &&
-                           !(errno == EINVAL || errno == EROFS)) {
+               if (close(fd_target)) {
+                       fprintf(stderr,
+                               "I/O error on %s: %s\n",
+                               DEVNAME(dev_target), strerror(errno));
+                       rc = -1;
+               }
+
+               if (target_temp) {
+                       int dir_fd;
+
+                       dir_fd = open(dname, O_DIRECTORY | O_RDONLY);
+                       if (dir_fd == -1)
                                fprintf(stderr,
-                                       "fsync failed on %s: %s\n",
-                                       DEVNAME(dev_current), strerror(errno));
-                       }
+                                       "Can't open %s: %s\n",
+                                       dname, strerror(errno));
 
-                       if (close(fd_target)) {
+                       if (rename(target_temp, DEVNAME(dev_target))) {
                                fprintf(stderr,
-                                       "I/O error on %s: %s\n",
-                                       DEVNAME(dev_target), strerror(errno));
+                                       "rename failed %s => %s: %s\n",
+                                       target_temp, DEVNAME(dev_target),
+                                       strerror(errno));
                                rc = -1;
                        }
+
+                       if (dir_fd != -1 && fsync(dir_fd))
+                               fprintf(stderr,
+                                       "fsync failed on %s: %s\n",
+                                       dname, strerror(errno));
+
+                       if (dir_fd != -1 && close(dir_fd))
+                               fprintf(stderr,
+                                       "I/O error on %s: %s\n",
+                                       dname, strerror(errno));
                }
+       }
+ exit:
+       return rc;
+}
+
+static int flash_io(int mode)
+{
+       int fd_current, rc;
+
+       /* dev_current: fd_current, erase_current */
+       fd_current = open(DEVNAME(dev_current), mode);
+       if (fd_current < 0) {
+               fprintf(stderr,
+                       "Can't open %s: %s\n",
+                       DEVNAME(dev_current), strerror(errno));
+               return -1;
+       }
+
+       if (mode == O_RDWR) {
+               rc = flash_io_write(fd_current);
        } else {
                rc = flash_read(fd_current);
        }
 
- exit:
        if (close(fd_current)) {
                fprintf(stderr,
                        "I/O error on %s: %s\n",