file_io.c: fix handling of EINTR

The old code would accidentally increment bytes_remaining...

diff --git a/src/file_io.c b/src/file_io.c
index 317a00d03b61df66d083c93162dcf5ed303256b6..3176ce6f64d4ba6e15c4ec6349f55b80be6468ef 100644 (file)
--- a/src/file_io.c
+++ b/src/file_io.c
@@ -31,7 +31,8 @@
 #include "wimlib/util.h"
 #include "wimlib/win32.h" /* For pread(), pwrite() replacements */
 
-/* Wrapper around read() that checks for errors keeps retrying until all
+/*
+ * Wrapper around read() that checks for errors and keeps retrying until all
  * requested bytes have been read or until end-of file has occurred.
  *
  * Return values:
@@ -42,27 +43,21 @@
 int
 full_read(struct filedes *fd, void *buf, size_t count)
 {
-       ssize_t bytes_read;
-       size_t bytes_remaining;
-
-       for (bytes_remaining = count;
-            bytes_remaining != 0;
-            bytes_remaining -= bytes_read, buf += bytes_read)
-       {
-               bytes_read = read(fd->fd, buf, bytes_remaining);
-               if (unlikely(bytes_read <= 0)) {
-                       if (bytes_read == 0) {
+       while (count) {
+               ssize_t ret = read(fd->fd, buf, count);
+               if (unlikely(ret <= 0)) {
+                       if (ret == 0) {
                                errno = 0;
                                return WIMLIB_ERR_UNEXPECTED_END_OF_FILE;
-                       } else if (errno == EINTR) {
-                               continue;
-                       } else {
-                               return WIMLIB_ERR_READ;
                        }
+                       if (errno == EINTR)
+                               continue;
+                       return WIMLIB_ERR_READ;
                }
+               buf += ret;
+               count -= ret;
+               fd->offset += ret;
        }
-       count -= bytes_remaining;
-       fd->offset += count;
        return 0;
 }
 
@@ -95,7 +90,8 @@ pipe_read(struct filedes *fd, void *buf, size_t count, off_t offset)
        return full_read(fd, buf, count);
 }
 
-/* Wrapper around pread() that checks for errors and keeps retrying until all
+/*
+ * Wrapper around pread() that checks for errors and keeps retrying until all
  * requested bytes have been read or until end-of file has occurred.  This also
  * transparently handle reading from pipe files, but the caller needs to be sure
  * the requested offset is greater than or equal to the current offset, or else
@@ -110,31 +106,27 @@ pipe_read(struct filedes *fd, void *buf, size_t count, off_t offset)
 int
 full_pread(struct filedes *fd, void *buf, size_t count, off_t offset)
 {
-       ssize_t bytes_read;
-       size_t bytes_remaining;
-
        if (fd->is_pipe)
                goto is_pipe;
 
-       for (bytes_remaining = count;
-            bytes_remaining != 0;
-            bytes_remaining -= bytes_read, buf += bytes_read,
-               offset += bytes_read)
-       {
-               bytes_read = pread(fd->fd, buf, bytes_remaining, offset);
-               if (unlikely(bytes_read <= 0)) {
-                       if (bytes_read == 0) {
+       while (count) {
+               ssize_t ret = pread(fd->fd, buf, count, offset);
+               if (unlikely(ret <= 0)) {
+                       if (ret == 0) {
                                errno = 0;
                                return WIMLIB_ERR_UNEXPECTED_END_OF_FILE;
-                       } else if (errno == EINTR) {
+                       }
+                       if (errno == EINTR)
                                continue;
-                       } else if (errno == ESPIPE) {
+                       if (errno == ESPIPE) {
                                fd->is_pipe = 1;
                                goto is_pipe;
-                       } else {
-                               return WIMLIB_ERR_READ;
                        }
+                       return WIMLIB_ERR_READ;
                }
+               buf += ret;
+               count -= ret;
+               offset += ret;
        }
        return 0;
 
@@ -142,7 +134,8 @@ is_pipe:
        return pipe_read(fd, buf, count, offset);
 }
 
-/* Wrapper around write() that checks for errors and keeps retrying until all
+/*
+ * Wrapper around write() that checks for errors and keeps retrying until all
  * requested bytes have been written.
  *
  * Return values:
@@ -152,49 +145,42 @@ is_pipe:
 int
 full_write(struct filedes *fd, const void *buf, size_t count)
 {
-       ssize_t bytes_written;
-       size_t bytes_remaining;
-
-       for (bytes_remaining = count;
-            bytes_remaining != 0;
-            bytes_remaining -= bytes_written, buf += bytes_written)
-       {
-               bytes_written = write(fd->fd, buf, bytes_remaining);
-               if (unlikely(bytes_written < 0)) {
+       while (count) {
+               ssize_t ret = write(fd->fd, buf, count);
+               if (unlikely(ret < 0)) {
                        if (errno == EINTR)
                                continue;
                        return WIMLIB_ERR_WRITE;
                }
+               buf += ret;
+               count -= ret;
+               fd->offset += ret;
        }
-       fd->offset += count;
        return 0;
 }
 
 
-/* Wrapper around pwrite() that checks for errors and keeps retrying until all
+/*
+ * Wrapper around pwrite() that checks for errors and keeps retrying until all
  * requested bytes have been written.
  *
  * Return values:
  *     WIMLIB_ERR_SUCCESS      (0)
  *     WIMLIB_ERR_WRITE        (errno set)
- * */
+ */
 int
 full_pwrite(struct filedes *fd, const void *buf, size_t count, off_t offset)
 {
-       ssize_t bytes_written;
-       size_t bytes_remaining;
-
-       for (bytes_remaining = count;
-            bytes_remaining != 0;
-            bytes_remaining -= bytes_written, buf += bytes_written,
-               offset += bytes_written)
-       {
-               bytes_written = pwrite(fd->fd, buf, bytes_remaining, offset);
-               if (unlikely(bytes_written < 0)) {
+       while (count) {
+               ssize_t ret = pwrite(fd->fd, buf, count, offset);
+               if (unlikely(ret < 0)) {
                        if (errno == EINTR)
                                continue;
                        return WIMLIB_ERR_WRITE;
                }
+               buf += ret;
+               count -= ret;
+               offset += ret;
        }
        return 0;
 }