From: Jeff Mahoney <jeffm@xxxxxxxx>
reiserfs_snprintf operates by handling the reiserfs-specific specifiers
itself and passing everything else to the generic vsnprintf routine.
That makes some assumptions about what the state of a va_list passed
by value to another function will be after the function returns. The
spec states that the contents of the va_list are undefined in that
case. It's worked so far but really only by the grace of gcc's internal
va_list implementation details.
This patch reworks reiserfs_snprintf to process one % directive at
a time. Since directives can consume more than one argument when field
width and precision * operators are used, that means we need to interpret
the format string more than we used to do. (The kernel vsnprintf
specifically doesn't handle %n). Otherwise, we can use an unsigned long
to hold the argument and let the generic snprintf do the type handling.
The only exception is long long arguments on platforms where long long
is larger than long, which need special handling.
The result is a va_list that is consistent within reiserfs_snprintf
and isn't passed by value anymore.
This isn't an ideal solution, but I didn't feel that teaching pointer()
about a %pV variant that didn't use va_copy would get much traction for
a number of reasons.
Reported-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jeff Mahoney <jeffm@xxxxxxxx>
---
fs/reiserfs/prints.c | 158 +++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 128 insertions(+), 30 deletions(-)
diff --git a/fs/reiserfs/prints.c b/fs/reiserfs/prints.c
index aead27d11e45..03ebdea9ddc7 100644
--- a/fs/reiserfs/prints.c
+++ b/fs/reiserfs/prints.c
@@ -6,6 +6,7 @@
#include <linux/fs.h>
#include "reiserfs.h"
#include <linux/string.h>
+#include <linux/ctype.h>
#include <linux/buffer_head.h>
#include <stdarg.h>
@@ -195,19 +196,94 @@ static size_t snprintf_disk_child(char *buf, size_t size, struct disk_child *dc)
dc_block_number(dc), dc_size(dc));
}
-static char *is_there_reiserfs_struct(char *fmt, int *what)
-{
- char *k = fmt;
-
- while ((k = strchr(k, '%')) != NULL) {
- if (k[1] == 'k' || k[1] == 'K' || k[1] == 'h' || k[1] == 't' ||
- k[1] == 'z' || k[1] == 'b' || k[1] == 'y' || k[1] == 'a') {
- *what = k[1];
+/*
+ * This should all just be %pV but pointer() does a va_copy and uses that
+ * instead of directly using args. That's the right thing to do pretty
+ * much every time, but it still forces us to identify how many arguments
+ * we need to pass for a single format spec. We need to be careful of u64
+ * on 32-bit since it'll need special handling. We can just use an
+ * unsigned long for everything else and vsnprintf will handling the
+ * typing itself.
+ */
+static int handle_generic_snprintf(char *p, size_t left,
+ const char *fmt, va_list *args)
+{
+ int width, precision, nargs = 1;
+ const char *spec = fmt;
+ unsigned long val;
+ int len = 0;
+
+ /* Skip flags */
+ while (1) {
+ bool found = true;
+ ++spec;
+ switch (*spec) {
+ case '-':
+ case '+':
+ case ' ':
+ case '#':
+ case '0':
break;
+ default:
+ found = false;
}
- k++;
+ if (!found)
+ break;
+ }
+
+ /* Field width */
+ if (isdigit(*spec)) {
+ while (isdigit(*++spec));
+ } else if (*spec == '*') {
+ nargs++;
+ spec++;
+ }
+
+ /* Precision */
+ if (*spec == '.') {
+ spec++;
+ if (isdigit(*spec)) {
+ while (isdigit(*++spec));
+ } else if (*spec == '*') {
+ nargs++;
+ spec++;
+ }
+ }
+
+ if (*spec == 'L' || !strncmp(spec, "ll", 2)) {
+ unsigned long long ullval;
+ if (nargs == 3) {
+ width = va_arg(*args, int);
+ precision = va_arg(*args, int);
+ ullval = va_arg(*args, unsigned long long);
+ len = snprintf(p, left, fmt, width, precision,
+ ullval);
+ } else if (nargs == 2) {
+ width = va_arg(*args, int);
+ ullval = va_arg(*args, unsigned long long);
+ len = snprintf(p, left, fmt, width, ullval);
+ } else {
+ ullval = va_arg(*args, unsigned long long);
+ len = snprintf(p, left, fmt, ullval);
+ }
+ return len;
+ }
+
+ if (nargs == 3) {
+ width = va_arg(*args, int);
+ precision = va_arg(*args, int);
+ val = va_arg(*args, unsigned long);
+ len = snprintf(p, left, fmt, width, precision, val);
+ } else if (nargs == 2) {
+ width = va_arg(*args, int);
+ val = va_arg(*args, unsigned long);
+ len = snprintf(p, left, fmt, width, val);
+ } else {
+ val = va_arg(*args, unsigned long);
+ len = snprintf(p, left, fmt, val);
}
- return k;
+
+ return len;
}
/*
@@ -237,23 +313,34 @@ static char fmt_buf[1024];
static int reiserfs_snprintf(char *p, size_t left, const char *fmt,
va_list *args)
{
+ size_t fmtlen = strlen(fmt);
+ const char *fmtend = fmt + fmtlen;
+ const char *end;
char *start = p;
- char *fmt1 = fmt_buf;
- char *k;
- int what;
- size_t len;
- spin_lock(&fmt_lock);
- strncpy(fmt1, fmt, sizeof(fmt_buf));
+ while (left && fmt != NULL && *fmt) {
+ bool reiserfs_spec = true;
+ int fmt_size;
+ size_t len;
- while ((k = is_there_reiserfs_struct(fmt1, &what)) != NULL) {
- *k = 0;
+ end = strchr(fmt + 1, '%');
- len = vsnprintf(p, left, fmt1, *args);
- p += len;
- left -= len;
+ /* Skip over %% */
+ while (end && !strncmp(end, "%%", 2))
+ end = strchr(end + 2, '%');
+
+ if (!end)
+ end = fmtend;
- switch (what) {
+ fmt_size = end - fmt;
+
+ /* Any text before the first % - could be entire string */
+ if (fmt[0] != '%') {
+ len = snprintf(p, left, "%.*s", fmt_size, fmt);
+ goto next;
+ }
+
+ switch (fmt[1]) {
case 'k':
len = snprintf_le_key(p, left,
va_arg(*args, struct reiserfs_key *));
@@ -286,19 +373,30 @@ static int reiserfs_snprintf(char *p, size_t left, const char *fmt,
len = snprintf_de_head(p, left,
va_arg(*args, struct reiserfs_de_head *));
break;
- }
+ default:
+ spin_lock(&fmt_lock);
+ strncpy(fmt_buf, fmt, fmt_size);
+ fmt_buf[fmt_size] = 0;
+ len = handle_generic_snprintf(p, left, fmt_buf, args);
+ spin_unlock(&fmt_lock);
+
+ reiserfs_spec = false;
+ break;
+ };
+
+ if (reiserfs_spec) {
+ p += len;
+ left -= len;
+
+ len = snprintf(p, left, "%.*s", fmt_size - 2, fmt + 2);
+ }
+next:
p += len;
left -= len;
- fmt1 = k + 2;
+ fmt = end;
}
- len = vsnprintf(p, left, fmt1, *args);
- p += len;
- left -= len;
-
- spin_unlock(&fmt_lock);
-
return p - start;
}
--
2.12.3
--
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