[Qemu-devel] [PATCH] qemu-io: Optionally verify only part of read data

[Kevin Wolf]

There are reasonable test cases where a read must span areas that are not
uniformly filled with one pattern but contains several parts. This makes -P
useless for them currently.

Introducing additional options which determine the part of the read data that
should be verified with the given pattern allows to check such reads.

Signed-off-by: Kevin Wolf <address@hidden>
---
 qemu-io.c |   51 +++++++++++++++++++++++++++++++++++++++++----------
 1 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/qemu-io.c b/qemu-io.c
index 405b6c5..60464e6 100644
--- a/qemu-io.c
+++ b/qemu-io.c
@@ -191,11 +191,13 @@ read_help(void)
 "\n"
 " Reads a segment of the currently open file, optionally dumping it to the\n"
 " standard output stream (with -v option) for subsequent inspection.\n"
+" -C, -- report statistics in a machine parsable format\n"
+" -l, -- length for pattern verification (only with -P)\n"
 " -p, -- use bdrv_pread to read the file\n"
 " -P, -- use a pattern to verify read data\n"
-" -C, -- report statistics in a machine parsable format\n"
-" -v, -- dump buffer to standard output\n"
 " -q, -- quite mode, do not show I/O statistics\n"
+" -s, -- start offset for pattern verification (only with -P)\n"
+" -v, -- dump buffer to standard output\n"
 "\n");
 }
 
@@ -204,18 +206,26 @@ read_f(int argc, char **argv)
 {
        struct timeval t1, t2;
        int Cflag = 0, pflag = 0, qflag = 0, vflag = 0;
+       int Pflag = 0, sflag = 0, lflag = 0;
        int c, cnt;
        char *buf;
        int64_t offset;
        int count, total;
-       int pattern = 0;
-       int Pflag = 0;
+       int pattern = 0, pattern_offset = 0, pattern_count = 0;
 
-       while ((c = getopt(argc, argv, "CpP:qv")) != EOF) {
+       while ((c = getopt(argc, argv, "Cl:pP:qs:v")) != EOF) {
                switch (c) {
                case 'C':
                        Cflag = 1;
                        break;
+               case 'l':
+                       lflag = 1;
+                       pattern_count = cvtnum(optarg);
+                       if (pattern_count < 0) {
+                               printf("non-numeric length argument -- %s\n", 
optarg);
+                               return 0;
+                       }
+                       break;
                case 'p':
                        pflag = 1;
                        break;
@@ -226,6 +236,14 @@ read_f(int argc, char **argv)
                case 'q':
                        qflag = 1;
                        break;
+               case 's':
+                       sflag = 1;
+                       pattern_offset = cvtnum(optarg);
+                       if (pattern_offset < 0) {
+                               printf("non-numeric length argument -- %s\n", 
optarg);
+                               return 0;
+                       }
+                       break;
                case 'v':
                        vflag = 1;
                        break;
@@ -250,6 +268,19 @@ read_f(int argc, char **argv)
                return 0;
        }
 
+    if (!Pflag && (lflag || sflag)) {
+        return command_usage(&read_cmd);
+    }
+
+    if (!lflag) {
+        pattern_count = count - pattern_offset;
+    }
+
+    if ((pattern_count < 0) || (pattern_count + pattern_offset > count))  {
+        printf("pattern verfication range exceeds end of read data\n");
+        return 0;
+    }
+
        if (!pflag)
                if (offset & 0x1ff) {
                        printf("offset %lld is not sector aligned\n",
@@ -278,12 +309,12 @@ read_f(int argc, char **argv)
        }
 
        if (Pflag) {
-               void* cmp_buf = malloc(count);
-               memset(cmp_buf, pattern, count);
-               if (memcmp(buf, cmp_buf, count)) {
+               void* cmp_buf = malloc(pattern_count);
+               memset(cmp_buf, pattern, pattern_count);
+               if (memcmp(buf + pattern_offset, cmp_buf, pattern_count)) {
                        printf("Pattern verification failed at offset %lld, "
                                "%d bytes\n",
-                               (long long) offset, count);
+                               (long long) offset + pattern_offset, 
pattern_count);
                }
                free(cmp_buf);
        }
@@ -309,7 +340,7 @@ static const cmdinfo_t read_cmd = {
        .cfunc          = read_f,
        .argmin         = 2,
        .argmax         = -1,
-       .args           = "[-aCpqv] [-P pattern ] off len",
+       .args           = "[-aCpqv] [-P pattern [-s off] [-l len]] off len",
        .oneline        = "reads a number of bytes at a specified offset",
        .help           = read_help,
 };
-- 
1.6.0.6