libreboot-utils/file: never retry file rw on zero

even with a timer, it's possible that on a buggy system,
we may keep writing even though the outcome is zero. if
a system comes back with zero bytes written, that is a
fatal bug and we should stop.

Signed-off-by: Leah Rowe <leah@libreboot.org>

4 files changed, 8 insertions, 23 deletions

diff --git a/util/libreboot-utils/include/common.h b/util/libreboot-utils/include/common.h
index 5058317c..2e8cb9a7 100644
--- a/util/libreboot-utils/include/common.h
+++ b/util/libreboot-utils/include/common.h
@@ -83,10 +83,6 @@
 #error "Unexpected bit layout"
 #endif
 
-#ifndef MAX_ZERO_RW_RETRY
-#define MAX_ZERO_RW_RETRY 5
-#endif
-
 #ifndef _FILE_OFFSET_BITS
 #define _FILE_OFFSET_BITS 64
 #endif
@@ -462,7 +458,7 @@ ssize_t rw_gbe_file_exact(int fd, unsigned char *mem, size_t nrw,
 
 int fsync_dir(const char *path);
 ssize_t rw_file_exact(int fd, unsigned char *mem, size_t len,
-    off_t off, int rw_type, size_t max_retries);
+    off_t off, int rw_type);
 ssize_t rw(int fd, void *mem, size_t nrw,
     off_t off, int rw_type);
 int io_args(int fd, void *mem, size_t nrw,
diff --git a/util/libreboot-utils/lib/command.c b/util/libreboot-utils/lib/command.c
index 526ad03b..be5e8712 100644
--- a/util/libreboot-utils/lib/command.c
+++ b/util/libreboot-utils/lib/command.c
@@ -493,7 +493,7 @@ cat_buf(unsigned char *b)
 		exitf("null pointer in cat command");
 
 	if (rw_file_exact(STDOUT_FILENO, b,
-	    GBE_PART_SIZE, 0, IO_WRITE, MAX_ZERO_RW_RETRY) < 0)
+	    GBE_PART_SIZE, 0, IO_WRITE) < 0)
 		exitf("stdout: cat");
 }
 void
diff --git a/util/libreboot-utils/lib/file.c b/util/libreboot-utils/lib/file.c
index d44d8cf9..741e6793 100644
--- a/util/libreboot-utils/lib/file.c
+++ b/util/libreboot-utils/lib/file.c
@@ -146,7 +146,7 @@ err_fsync_dir:
 
 ssize_t
 rw_file_exact(int fd, unsigned char *mem, size_t nrw,
-    off_t off, int rw_type, size_t max_retries)
+    off_t off, int rw_type)
 {
 	int saved_errno = errno;
 	ssize_t rval = 0;
@@ -154,7 +154,6 @@ rw_file_exact(int fd, unsigned char *mem, size_t nrw,
 	size_t nrw_cur;
 	off_t off_cur;
 	void *mem_cur;
-	size_t retries_on_zero = 0;
 	errno = 0;
 
 	if (io_args(fd, mem, nrw, off, rw_type) == -1)
@@ -178,17 +177,8 @@ rw_file_exact(int fd, unsigned char *mem, size_t nrw,
 
 		off_cur = off + (off_t)rc;
 
-		if ((rval = rw(fd, mem_cur, nrw_cur, off_cur, rw_type)) < 0)
-			goto err_rw_file_exact;
-
-		if (rval == 0) {
-			if (retries_on_zero++ < max_retries)
-				continue;
-
+		if ((rval = rw(fd, mem_cur, nrw_cur, off_cur, rw_type)) <= 0)
 			goto err_rw_file_exact;
-		}
-
-		retries_on_zero = 0;
 	}
 
 	if (if_err((size_t)rc != nrw, EIO) ||
diff --git a/util/libreboot-utils/lib/io.c b/util/libreboot-utils/lib/io.c
index f8e67977..81f9f52a 100644
--- a/util/libreboot-utils/lib/io.c
+++ b/util/libreboot-utils/lib/io.c
@@ -109,7 +109,7 @@ read_file(void)
 	/* read main file
 	 */
 	_r = rw_file_exact(f->gbe_fd, f->buf, f->gbe_file_size,
-	    0, IO_PREAD, MAX_ZERO_RW_RETRY);
+	    0, IO_PREAD);
 
 	if (_r < 0)
 		exitf("%s: read failed", f->fname);
@@ -117,7 +117,7 @@ read_file(void)
 	/* copy to tmpfile
 	 */
 	_r = rw_file_exact(f->tmp_fd, f->buf, f->gbe_file_size,
-	    0, IO_PWRITE, MAX_ZERO_RW_RETRY);
+	    0, IO_PWRITE);
 
 	if (_r < 0)
 		exitf("%s: %s: copy failed",
@@ -140,7 +140,7 @@ read_file(void)
 		exitf("%s: fsync (tmpfile copy)", f->tname);
 
 	_r = rw_file_exact(f->tmp_fd, f->bufcmp, f->gbe_file_size,
-	    0, IO_PREAD, MAX_ZERO_RW_RETRY);
+	    0, IO_PREAD);
 
 	if (_r < 0)
 		exitf("%s: read failed (cmp)", f->tname);
@@ -556,8 +556,7 @@ rw_gbe_file_exact(int fd, unsigned char *mem, size_t nrw,
 	if (nrw > (size_t)GBE_PART_SIZE)
 		goto err_rw_gbe_file_exact;
 
-	r = rw_file_exact(fd, mem, nrw, off, rw_type,
-	    MAX_ZERO_RW_RETRY);
+	r = rw_file_exact(fd, mem, nrw, off, rw_type);
 
 	return rw_over_nrw(r, nrw);