[Qemu-devel] [PATCH 6/6] cutils: Make strtosz & friends leave follow set to callers

[Markus Armbruster]

strtosz() & friends require the size to be at the end of the string,
or be followed by whitespace or ','.  I find this surprising, because
the name suggests it works like strtol().

The check simplifies callers that accept exactly that follow set
slightly.  No such callers exist.

The check is redundant for callers that accept a smaller follow set,
and thus need to check themselves anyway.  Right now, this is the case
for all but one caller.  All of them neglected to check, or checked
incorrectly, but the previous few commits fixed them up.

Finally, the check is problematic for callers that accept a larger
follow set.  This is the case in monitor_parse_command().
Fortunately, the problems there are relatively harmless.

monitor_parse_command() uses strtosz() for argument type 'o'.  When
the last argument is of type 'o', a trailing ',' is diagnosed
differently than other trailing junk:

    (qemu) migrate_set_speed 1x
    invalid size
    (qemu) migrate_set_speed 1,
    migrate_set_speed: extraneous characters at the end of line

A related inconsistency exists with non-last arguments.  No such
command exists, but let's use memsave to explore the inconsistency.

The monitor permits, but does not require whitespace between
arguments.  For instance, "memsave (1-1)1024foo" is parsed as command
memsave with three arguments 0, 1024 and "foo".  Yes, this is daft,
but at least it's consistently daft.

If I change memsave's second argument from 'i' to 'o', then "memsave
(1-1)1foo" is rejected, because the size is followed by an 'f'.  But
"memsave (1-1)1," is still accepted, and duly saves to file ",".

We don't have any users of strtosz that profit from the check.  In the
users we have, it appears to encourage sloppy error checking, or gets
in the way.  Drop the bothersome check.

Signed-off-by: Markus Armbruster <address@hidden>
---
 cutils.c |   70 +++++++++++++++++++++++---------------------------------------
 1 files changed, 26 insertions(+), 44 deletions(-)

diff --git a/cutils.c b/cutils.c
index 55b0596..6db6304 100644
--- a/cutils.c
+++ b/cutils.c
@@ -315,18 +315,34 @@ int fcntl_setfl(int fd, int flag)
 }
 #endif
 
+static int64_t suffix_mul(char suffix, int64_t unit)
+{
+    switch (qemu_toupper(suffix)) {
+    case STRTOSZ_DEFSUFFIX_B:
+        return 1;
+    case STRTOSZ_DEFSUFFIX_KB:
+        return unit;
+    case STRTOSZ_DEFSUFFIX_MB:
+        return unit * unit;
+    case STRTOSZ_DEFSUFFIX_GB:
+        return unit * unit * unit;
+    case STRTOSZ_DEFSUFFIX_TB:
+        return unit * unit * unit * unit;
+    }
+    return -1;
+}
+
 /*
  * Convert string to bytes, allowing either B/b for bytes, K/k for KB,
  * M/m for MB, G/g for GB or T/t for TB. End pointer will be returned
- * in *end, if not NULL. A valid value must be terminated by
- * whitespace, ',' or '\0'. Return -1 on error.
+ * in *end, if not NULL. Return -1 on error.
  */
 int64_t strtosz_suffix_unit(const char *nptr, char **end,
                             const char default_suffix, int64_t unit)
 {
     int64_t retval = -1;
     char *endptr;
-    unsigned char c, d;
+    unsigned char c;
     int mul_required = 0;
     double val, mul, integral, fraction;
 
@@ -339,51 +355,17 @@ int64_t strtosz_suffix_unit(const char *nptr, char **end,
     if (fraction != 0) {
         mul_required = 1;
     }
-    /*
-     * Any whitespace character is fine for terminating the number,
-     * in addition we accept ',' to handle strings where the size is
-     * part of a multi token argument.
-     */
     c = *endptr;
-    d = c;
-    if (qemu_isspace(c) || c == '\0' || c == ',') {
-        c = 0;
-        d = default_suffix;
+    mul = suffix_mul(c, unit);
+    if (mul >= 0) {
+        endptr++;
+    } else {
+        mul = suffix_mul(default_suffix, unit);
+        assert(mul >= 0);
     }
-    switch (qemu_toupper(d)) {
-    case STRTOSZ_DEFSUFFIX_B:
-        mul = 1;
-        if (mul_required) {
-            goto fail;
-        }
-        break;
-    case STRTOSZ_DEFSUFFIX_KB:
-        mul = unit;
-        break;
-    case STRTOSZ_DEFSUFFIX_MB:
-        mul = unit * unit;
-        break;
-    case STRTOSZ_DEFSUFFIX_GB:
-        mul = unit * unit * unit;
-        break;
-    case STRTOSZ_DEFSUFFIX_TB:
-        mul = unit * unit * unit * unit;
-        break;
-    default:
+    if (mul == 1 && mul_required) {
         goto fail;
     }
-    /*
-     * If not terminated by whitespace, ',', or \0, increment endptr
-     * to point to next character, then check that we are terminated
-     * by an appropriate separating character, ie. whitespace, ',', or
-     * \0. If not, we are seeing trailing garbage, thus fail.
-     */
-    if (c != 0) {
-        endptr++;
-        if (!qemu_isspace(*endptr) && *endptr != ',' && *endptr != 0) {
-            goto fail;
-        }
-    }
     if ((val * mul >= INT64_MAX) || val < 0) {
         goto fail;
     }
-- 
1.7.6.4