From 0ff69e539fc76f718bb7afd41a309bea2bd5155d Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Wed, 21 Jun 2023 19:46:50 -0500
Subject: [PATCH] Don't delete bunzip2 input file on error (Reported by Frank
 Busse).

Changed error path to consistently return error string instead of error_exit()
in the middle, which involved a longjmp at one awkward point but can probably
work NOFORK now if necessary? Should also allow bunzip2 to continue to
process rest of command line files on error instead of stopping early,
but bzcat doesn't as a design choice.
---
 toys/other/bzcat.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/toys/other/bzcat.c b/toys/other/bzcat.c
index ebe93298..1d48a115 100644
--- a/toys/other/bzcat.c
+++ b/toys/other/bzcat.c
@@ -11,7 +11,7 @@
  * No standard.
 
 
-USE_BZCAT(NEWTOY(bzcat, NULL, TOYFLAG_USR|TOYFLAG_BIN))
+USE_BZCAT(NEWTOY(bzcat, 0, TOYFLAG_USR|TOYFLAG_BIN))
 USE_BUNZIP2(NEWTOY(bunzip2, "cftkv", TOYFLAG_USR|TOYFLAG_BIN))
 
 config BUNZIP2
@@ -59,6 +59,8 @@ config BZCAT
 #define RETVAL_NOT_BZIP_DATA     (-1)
 #define RETVAL_DATA_ERROR        (-2)
 #define RETVAL_OBSOLETE_INPUT    (-3)
+#define RETVAL_EOF_IN            (-4)
+#define RETVAL_EOF_OUT           (-5)
 
 // This is what we know about each huffman coding group
 struct group_data {
@@ -118,7 +120,7 @@ static unsigned int get_bits(struct bunzip_data *bd, char bits_wanted)
     // If we need to read more data from file into byte buffer, do so
     if (bd->inbufPos == bd->inbufCount) {
       if (0 >= (bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE)))
-        error_exit("input EOF");
+        longjmp((void *)toybuf, RETVAL_EOF_IN);
       bd->inbufPos = 0;
     }
 
@@ -440,13 +442,15 @@ static int read_huffman_data(struct bunzip_data *bd, struct bwdata *bw)
 }
 
 // Flush output buffer to disk
-static void flush_bunzip_outbuf(struct bunzip_data *bd, int out_fd)
+static int flush_bunzip_outbuf(struct bunzip_data *bd, int out_fd)
 {
   if (bd->outbufPos) {
     if (write(out_fd, bd->outbuf, bd->outbufPos) != bd->outbufPos)
-      error_exit("output EOF");
+      return RETVAL_EOF_OUT;
     bd->outbufPos = 0;
   }
+
+  return 0;
 }
 
 static void burrows_wheeler_prep(struct bunzip_data *bd, struct bwdata *bw)
@@ -561,7 +565,8 @@ static int write_bunzip_data(struct bunzip_data *bd, struct bwdata *bw,
 
       // Output bytes to buffer, flushing to file if necessary
       while (copies--) {
-        if (bd->outbufPos == IOBUF_SIZE) flush_bunzip_outbuf(bd, out_fd);
+        if (bd->outbufPos == IOBUF_SIZE && flush_bunzip_outbuf(bd, out_fd))
+          return RETVAL_EOF_OUT;
         bd->outbuf[bd->outbufPos++] = outbyte;
         bw->dataCRC = (bw->dataCRC << 8)
                 ^ bd->crc32Table[(bw->dataCRC >> 24) ^ outbyte];
@@ -643,17 +648,18 @@ static int start_bunzip(struct bunzip_data **bdp, int src_fd, char *inbuf,
 static char *bunzipStream(int src_fd, int dst_fd)
 {
   struct bunzip_data *bd;
-  char *bunzip_errors[] = {0, "not bzip", "bad data", "old format"};
+  char *bunzip_errors[] = {0, "not bzip", "bad data", "old format", "in EOF",
+    "out EOF"};
   int i, j;
 
-  if (!(i = start_bunzip(&bd,src_fd, 0, 0))) {
-    i = write_bunzip_data(bd,bd->bwdata, dst_fd, 0, 0);
+  if (!(i = setjmp((void *)toybuf)) && !(i = start_bunzip(&bd, src_fd, 0, 0))) {
+    i = write_bunzip_data(bd, bd->bwdata, dst_fd, 0, 0);
     if (i==RETVAL_LAST_BLOCK) {
       if (bd->bwdata[0].headerCRC==bd->totalCRC) i = 0;
       else i = RETVAL_DATA_ERROR;
     }
   }
-  flush_bunzip_outbuf(bd, dst_fd);
+  if (!i) i = flush_bunzip_outbuf(bd, dst_fd);
 
   for (j=0; j<THREADS; j++) free(bd->bwdata[j].dbuf);
   free(bd);
@@ -695,7 +701,7 @@ static void do_bunzip2(int fd, char *name)
   if (FLAG(v)) printf("%s:", name);
   err = bunzipStream(fd, outfd);
   if (FLAG(v)) {
-    printf("%s\n", err ? err : "ok");
+    printf("%s\n", err ? : "ok");
     toys.exitval |= !!err;
   } else if (err) error_msg_raw(err);
 
@@ -704,7 +710,7 @@ static void do_bunzip2(int fd, char *name)
     if (FLAG(k)) {
       free(tmp);
       tmp = 0;
-    } else {
+    } else if (!err) {
       if (dotbz) *dotbz = '.';
       if (!unlink(name)) perror_msg_raw(name);
     }
-- 
2.39.2