nanddump: check write function result for errors

Errors may happen, it's e.g. easy on embedded devices to run out of space
when dumping big partitions. This patch adds a helper function for
writing. It deals with partial writes and just returns 0 on success or
error number.

The old code didn't check for errors at all which could result in
incomplete dumps without exiting with an error.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/nand-utils/nanddump.c b/nand-utils/nanddump.c
index 300aca680781dad090d4679cbe232cb0e1b4b73b..ec173149bb87441d6991c8e1b80896b17b3d7b19 100644 (file)
--- a/nand-utils/nanddump.c
+++ b/nand-utils/nanddump.c
@@ -293,6 +293,31 @@ nil:
        linebuf[lx++] = '\0';
 }
 
+/**
+ * ofd_write - writes whole buffer to the file associated with a descriptor
+ *
+ * On failure an error (negative number) is returned. Otherwise 0 is returned.
+ */
+static int ofd_write(int ofd, const void *buf, size_t nbyte)
+{
+       const unsigned char *data = buf;
+       ssize_t bytes;
+
+       while (nbyte) {
+               bytes = write(ofd, data, nbyte);
+               if (bytes < 0) {
+                       int err = -errno;
+
+                       sys_errmsg("Unable to write to output");
+
+                       return err;
+               }
+               data += bytes;
+               nbyte -= bytes;
+       }
+
+       return 0;
+}
 
 /*
  * Main program
@@ -309,6 +334,7 @@ int main(int argc, char * const argv[])
        bool eccstats = false;
        unsigned char *readbuf = NULL, *oobbuf = NULL;
        libmtd_t mtd_desc;
+       int err;
 
        process_options(argc, argv);
 
@@ -443,15 +469,20 @@ int main(int argc, char * const argv[])
                        for (i = 0; i < bs; i += PRETTY_ROW_SIZE) {
                                pretty_dump_to_buffer(readbuf + i, PRETTY_ROW_SIZE,
                                                pretty_buf, PRETTY_BUF_LEN, true, canonical, ofs + i);
-                               write(ofd, pretty_buf, strlen(pretty_buf));
+                               err = ofd_write(ofd, pretty_buf, strlen(pretty_buf));
+                               if (err)
+                                       goto closeall;
                        }
                } else {
                        /* Write requested length if oob is omitted */
                        size_t size_left = end_addr - ofs;
                        if (omitoob && (size_left < bs))
-                               write(ofd, readbuf, size_left);
+                               err = ofd_write(ofd, readbuf, size_left);
                        else
-                               write(ofd, readbuf, bs);
+                               err = ofd_write(ofd, readbuf, bs);
+
+                       if (err)
+                               goto closeall;
                }
 
                if (omitoob)
@@ -472,10 +503,15 @@ int main(int argc, char * const argv[])
                        for (i = 0; i < mtd.oob_size; i += PRETTY_ROW_SIZE) {
                                pretty_dump_to_buffer(oobbuf + i, mtd.oob_size - i,
                                                pretty_buf, PRETTY_BUF_LEN, false, canonical, 0);
-                               write(ofd, pretty_buf, strlen(pretty_buf));
+                               err = ofd_write(ofd, pretty_buf, strlen(pretty_buf));
+                               if (err)
+                                       goto closeall;
                        }
-               } else
-                       write(ofd, oobbuf, mtd.oob_size);
+               } else {
+                       err = ofd_write(ofd, oobbuf, mtd.oob_size);
+                       if (err)
+                               goto closeall;
+               }
        }
 
        /* Close the output file and MTD device, free memory */