From: Ben Pfaff <blp@cs.stanford.edu>
Date: Sat, 22 May 2010 18:28:18 +0000 (-0700)
Subject: dissect-sysfile: Allow padding compressed data at end of file without error.
X-Git-Tag: v0.7.6~419
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c17158f059ed075cbac2fd6e6b3be8ea9ba5de6c;p=pspp-builds.git

dissect-sysfile: Allow padding compressed data at end of file without error.

Compressed data in a system file can end either with a special opcode or
by padding out the last set of opcodes to an 8-byte boundary with null
bytes.  Until now, dissect-sysfile has complained about last with
"unexpected end of file".  This commit fixes the problem.
---

diff --git a/tests/dissect-sysfile.c b/tests/dissect-sysfile.c
index 4fc610a9..6aff2650 100644
--- a/tests/dissect-sysfile.c
+++ b/tests/dissect-sysfile.c
@@ -102,6 +102,7 @@ static void sys_error (struct sfm_reader *, const char *, ...)
      NO_RETURN;
 
 static void read_bytes (struct sfm_reader *, void *, size_t);
+static bool try_read_bytes (struct sfm_reader *, void *, size_t);
 static int read_int (struct sfm_reader *);
 static int64_t read_int64 (struct sfm_reader *);
 static double read_float (struct sfm_reader *);
@@ -1093,7 +1094,13 @@ read_compressed_data (struct sfm_reader *r)
           if (opcode_idx >= N_OPCODES)
             {
               opcode_ofs = ftello (r->file);
-              read_bytes (r, opcodes, 8);
+              if (i == 0)
+                {
+                  if (!try_read_bytes (r, opcodes, 8))
+                    return;
+                }
+              else
+                read_bytes (r, opcodes, 8);
               opcode_idx = 0;
             }
           opcode = opcodes[opcode_idx];
@@ -1360,6 +1367,16 @@ read_bytes (struct sfm_reader *r, void *buf, size_t byte_cnt)
   read_bytes_internal (r, false, buf, byte_cnt);
 }
 
+/* Reads BYTE_CNT bytes into BUF.
+   Returns true if exactly BYTE_CNT bytes are successfully read.
+   Returns false if an immediate end-of-file is encountered.
+   Aborts if an I/O error or a partial read occurs. */
+static bool
+try_read_bytes (struct sfm_reader *r, void *buf, size_t byte_cnt)
+{
+  return read_bytes_internal (r, true, buf, byte_cnt);
+}
+
 /* Reads a 32-bit signed integer from R and returns its value in
    host format. */
 static int