[U-Boot] [PATCH 2/2] tools: mkenvimage: Always consider non-regular files

[Andre Przywara]

At the moment mkenvimage has two separate read paths: One to read from
a potential pipe, while dynamically increasing the buffer size, and a
second one using mmap(2), using the input file's size. This is
problematic for two reasons:
- The "pipe" path will be chosen if the input filename is missing or
  "-".  Any named, but non-regular file will use the other path, which
  typically will cause mmap() to fail:
  $ mkenvimage -s 256 -o out <(echo "foo=bar")
- There is no reason to have *two* ways of reading a file, since the
  "pipe way" will always work, even for regular files.

Fix this (and simplify the code on the way) by always using the method
of dynamically resizing the buffer. The existing distinction between
the two cases will merely be used to use the open() syscall or not.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
 tools/mkenvimage.c | 70 ++++++++++++++++--------------------------------------
 1 file changed, 21 insertions(+), 49 deletions(-)

diff --git a/tools/mkenvimage.c b/tools/mkenvimage.c
index ffaebd5565..a8eebab6c3 100644
--- a/tools/mkenvimage.c
+++ b/tools/mkenvimage.c
@@ -65,10 +65,12 @@ long int xstrtol(const char *s)
 	exit(EXIT_FAILURE);
 }
 
+#define CHUNK_SIZE 4096
+
 int main(int argc, char **argv)
 {
 	uint32_t crc, targetendian_crc;
-	const char *txt_filename = NULL, *bin_filename = NULL;
+	const char *bin_filename = NULL;
 	int txt_fd, bin_fd;
 	unsigned char *dataptr, *envptr;
 	unsigned char *filebuf = NULL;
@@ -76,12 +78,11 @@ int main(int argc, char **argv)
 	int bigendian = 0;
 	int redundant = 0;
 	unsigned char padbyte = 0xff;
+	int readbytes = 0;
 
 	int option;
 	int ret = EXIT_SUCCESS;
 
-	struct stat txt_file_stat;
-
 	int fp, ep;
 	const char *prg;
 
@@ -156,62 +157,33 @@ int main(int argc, char **argv)
 
 	/* Open the input file ... */
 	if (optind >= argc || strcmp(argv[optind], "-") == 0) {
-		int readbytes = 0;
-		int readlen = sizeof(*envptr) * 4096;
 		txt_fd = STDIN_FILENO;
-
-		do {
-			filebuf = realloc(filebuf, filesize + readlen);
-			if (!filebuf) {
-				fprintf(stderr, "Can't realloc memory for the input file buffer\n");
-				return EXIT_FAILURE;
-			}
-			readbytes = read(txt_fd, filebuf + filesize, readlen);
-			if (readbytes < 0) {
-				fprintf(stderr, "Error while reading stdin: %s\n",
-						strerror(errno));
-				return EXIT_FAILURE;
-			}
-			filesize += readbytes;
-		} while (readbytes > 0);
 	} else {
-		txt_filename = argv[optind];
-		txt_fd = open(txt_filename, O_RDONLY);
+		txt_fd = open(argv[optind], O_RDONLY);
 		if (txt_fd == -1) {
 			fprintf(stderr, "Can't open \"%s\": %s\n",
-					txt_filename, strerror(errno));
+					argv[optind], strerror(errno));
 			return EXIT_FAILURE;
 		}
-		/* ... and check it */
-		ret = fstat(txt_fd, &txt_file_stat);
-		if (ret == -1) {
-			fprintf(stderr, "Can't stat() on \"%s\": %s\n",
-					txt_filename, strerror(errno));
+	}
+
+	do {
+		filebuf = realloc(filebuf, filesize + CHUNK_SIZE);
+		if (!filebuf) {
+			fprintf(stderr, "Can't realloc memory for the input file buffer\n");
 			return EXIT_FAILURE;
 		}
-
-		filesize = txt_file_stat.st_size;
-
-		filebuf = mmap(NULL, sizeof(*envptr) * filesize, PROT_READ,
-			       MAP_PRIVATE, txt_fd, 0);
-		if (filebuf == MAP_FAILED) {
-			fprintf(stderr, "mmap (%zu bytes) failed: %s\n",
-					sizeof(*envptr) * filesize,
-					strerror(errno));
-			fprintf(stderr, "Falling back to read()\n");
-
-			filebuf = malloc(sizeof(*envptr) * filesize);
-			ret = read(txt_fd, filebuf, sizeof(*envptr) * filesize);
-			if (ret != sizeof(*envptr) * filesize) {
-				fprintf(stderr, "Can't read the whole input file (%zu bytes): %s\n",
-					sizeof(*envptr) * filesize,
-					strerror(errno));
-
-				return EXIT_FAILURE;
-			}
+		readbytes = read(txt_fd, filebuf + filesize, CHUNK_SIZE);
+		if (readbytes < 0) {
+			fprintf(stderr, "Error while reading: %s\n",
+				strerror(errno));
+			return EXIT_FAILURE;
 		}
+		filesize += readbytes;
+	} while (readbytes > 0);
+
+	if (txt_fd != STDIN_FILENO)
 		ret = close(txt_fd);
-	}
 
 	/* Parse a byte at time until reaching the file OR until the environment fills
 	 * up. Check ep against envsize - 1 to allow for extra trailing '\0'. */
-- 
2.14.5