Eliminated seeks so that we work correctly on pipes, and removed reliance on

undefined evaluation ordering.  Thanks to Anthony Towns for explanation and
solution.

3 files changed, 27 insertions, 6 deletions

diff --git a/archival/libunarchive/decompress_unzip.c b/archival/libunarchive/decompress_unzip.c
index b843ec812..9568c2870 100644
--- a/archival/libunarchive/decompress_unzip.c
+++ b/archival/libunarchive/decompress_unzip.c
@@ -904,6 +904,7 @@ extern int unzip(FILE *l_in_file, FILE *l_out_file)
         int method;
         typedef void (*sig_type) (int);
         int exit_code=0;        /* program exit code */
+        int i;
 
         in_file = l_in_file;
         out_file = l_out_file;
@@ -949,10 +950,16 @@ extern int unzip(FILE *l_in_file, FILE *l_out_file)
         flags = (unsigned char) fgetc(in_file);
 
         /* Ignore time stamp(4), extra flags(1), OS type(1) */
-        fseek(in_file, 6, SEEK_CUR);
+        for (i = 0; i < 6; i++)
+                fgetc(in_file);
 
         if ((flags & extra_field) != 0) {
-                fseek(in_file, (size_t) fgetc(in_file) + ((size_t)fgetc(in_file) << 8), SEEK_CUR);
+                size_t extra;
+                extra = fgetc(in_file);
+                extra += fgetc(in_file) << 8;
+
+                for (i = 0; i < extra; i++)
+                        fgetc(in_file);
         }
 
         /* Discard original name if any */
diff --git a/archival/libunarchive/unzip.c b/archival/libunarchive/unzip.c
index b843ec812..9568c2870 100644
--- a/archival/libunarchive/unzip.c
+++ b/archival/libunarchive/unzip.c
@@ -904,6 +904,7 @@ extern int unzip(FILE *l_in_file, FILE *l_out_file)
         int method;
         typedef void (*sig_type) (int);
         int exit_code=0;        /* program exit code */
+        int i;
 
         in_file = l_in_file;
         out_file = l_out_file;
@@ -949,10 +950,16 @@ extern int unzip(FILE *l_in_file, FILE *l_out_file)
         flags = (unsigned char) fgetc(in_file);
 
         /* Ignore time stamp(4), extra flags(1), OS type(1) */
-        fseek(in_file, 6, SEEK_CUR);
+        for (i = 0; i < 6; i++)
+                fgetc(in_file);
 
         if ((flags & extra_field) != 0) {
-                fseek(in_file, (size_t) fgetc(in_file) + ((size_t)fgetc(in_file) << 8), SEEK_CUR);
+                size_t extra;
+                extra = fgetc(in_file);
+                extra += fgetc(in_file) << 8;
+
+                for (i = 0; i < extra; i++)
+                        fgetc(in_file);
         }
 
         /* Discard original name if any */
diff --git a/libbb/unzip.c b/libbb/unzip.c
index b843ec812..9568c2870 100644
--- a/libbb/unzip.c
+++ b/libbb/unzip.c
@@ -904,6 +904,7 @@ extern int unzip(FILE *l_in_file, FILE *l_out_file)
         int method;
         typedef void (*sig_type) (int);
         int exit_code=0;        /* program exit code */
+        int i;
 
         in_file = l_in_file;
         out_file = l_out_file;
@@ -949,10 +950,16 @@ extern int unzip(FILE *l_in_file, FILE *l_out_file)
         flags = (unsigned char) fgetc(in_file);
 
         /* Ignore time stamp(4), extra flags(1), OS type(1) */
-        fseek(in_file, 6, SEEK_CUR);
+        for (i = 0; i < 6; i++)
+                fgetc(in_file);
 
         if ((flags & extra_field) != 0) {
-                fseek(in_file, (size_t) fgetc(in_file) + ((size_t)fgetc(in_file) << 8), SEEK_CUR);
+                size_t extra;
+                extra = fgetc(in_file);
+                extra += fgetc(in_file) << 8;
+
+                for (i = 0; i < extra; i++)
+                        fgetc(in_file);
         }
 
         /* Discard original name if any */