archival: added O_TRUNC so that when we overwrite files on unpack,

          we truncate them. Also spotted & fixed hard to trigger bug
          with extension handling.

5 files changed, 19 insertions, 13 deletions

diff --git a/archival/bunzip2.c b/archival/bunzip2.c
index a970aeb20..9810e0290 100644
--- a/archival/bunzip2.c
+++ b/archival/bunzip2.c
@@ -41,17 +41,20 @@ int bunzip2_main(int argc, char **argv)
 
         if (filename) {
                 struct stat stat_buf;
-                char *extension=filename+strlen(filename)-4;
-                if (strcmp(extension, ".bz2") != 0) {
+                /* extension = filename+strlen(filename)-4 is buggy:
+                 * strlen may be less than 4 */
+                char *extension = strrchr(filename, '.');
+                if (!extension || strcmp(extension, ".bz2") != 0) {
                         bb_error_msg_and_die("Invalid extension");
                 }
                 xstat(filename, &stat_buf);
-                *extension=0;
-                dst_fd = xopen3(filename, O_WRONLY | O_CREAT, stat_buf.st_mode);
+                *extension = '\0';
+                dst_fd = xopen3(filename, O_WRONLY | O_CREAT | O_TRUNC,
+                                stat_buf.st_mode);
         } else dst_fd = STDOUT_FILENO;
         status = uncompressStream(src_fd, dst_fd);
         if(filename) {
-                if (!status) filename[strlen(filename)]='.';
+                if (!status) filename[strlen(filename)] = '.';
                 if (unlink(filename) < 0) {
                         bb_error_msg_and_die("Couldn't remove %s", filename);
                 }
diff --git a/archival/gunzip.c b/archival/gunzip.c
index 3a1d1cb61..7be94e1b8 100644
--- a/archival/gunzip.c
+++ b/archival/gunzip.c
@@ -98,7 +98,8 @@ int gunzip_main(int argc, char **argv)
                         }
 
                         /* Open output file (with correct permissions) */
-                        dst_fd = xopen3(new_path, O_WRONLY | O_CREAT, stat_buf.st_mode);
+                        dst_fd = xopen3(new_path, O_WRONLY | O_CREAT | O_TRUNC,
+                                        stat_buf.st_mode);
 
                         /* If unzip succeeds remove the old file */
                         delete_path = old_path;
diff --git a/archival/uncompress.c b/archival/uncompress.c
index ca775c787..8c466ebdf 100644
--- a/archival/uncompress.c
+++ b/archival/uncompress.c
@@ -55,7 +55,8 @@ int uncompress_main(int argc, char **argv)
 
                         /* Open output file */
                         xstat(compressed_file, &stat_buf);
-                        dst_fd = xopen3(uncompressed_file, O_WRONLY | O_CREAT,
+                        dst_fd = xopen3(uncompressed_file,
+                                        O_WRONLY | O_CREAT | O_TRUNC,
                                         stat_buf.st_mode);
 
                         /* If unzip succeeds remove the old file */
diff --git a/archival/unlzma.c b/archival/unlzma.c
index fbd207ca1..00acea6e0 100644
--- a/archival/unlzma.c
+++ b/archival/unlzma.c
@@ -37,14 +37,15 @@ int unlzma_main(int argc, char **argv)
 
         if (filename) {
                 struct stat stat_buf;
-                char *extension = filename + strlen(filename) - 5;
-
-                if (strcmp(extension, ".lzma") != 0) {
+                /* bug: char *extension = filename + strlen(filename) - 5; */
+                char *extension = strrchr(filename, '.');
+                if (!extension || strcmp(extension, ".lzma") != 0) {
                         bb_error_msg_and_die("Invalid extension");
                 }
                 xstat(filename, &stat_buf);
-                *extension = 0;
-                dst_fd = xopen3(filename, O_WRONLY | O_CREAT, stat_buf.st_mode);
+                *extension = '\0';
+                dst_fd = xopen3(filename, O_WRONLY | O_CREAT | O_TRUNC,
+                                stat_buf.st_mode);
         } else
                 dst_fd = STDOUT_FILENO;
         status = unlzma(src_fd, dst_fd);
diff --git a/archival/unzip.c b/archival/unzip.c
index 6dd1d3597..709ebf81a 100644
--- a/archival/unzip.c
+++ b/archival/unzip.c
@@ -333,7 +333,7 @@ int unzip_main(int argc, char **argv)
                         overwrite = o_always;
                 case 'y': /* Open file and fall into unzip */
                         unzip_create_leading_dirs(dst_fn);
-                        dst_fd = xopen3(dst_fn, O_WRONLY | O_CREAT, 0777);
+                        dst_fd = xopen3(dst_fn, O_WRONLY | O_CREAT | O_TRUNC, 0777);
                 case -1: /* Unzip */
                         if (verbosity == v_normal) {
                                 printf("  inflating: %s\n", dst_fn);