[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
[tor-commits] [tor/master] Refactor unsigned int hex formatting out of format_helper_exit_status() in util.c
commit c21af69f29ca5a55385a926fdac4a8e6c8fb6d37
Author: Andrea Shepard <andrea@xxxxxxxxxxxxxxxxxxx>
Date: Wed Jun 20 14:43:50 2012 -0700
Refactor unsigned int hex formatting out of format_helper_exit_status() in util.c
---
src/common/util.c | 154 +++++++++++++++++++++++++++++++++--------------------
src/common/util.h | 2 +
2 files changed, 99 insertions(+), 57 deletions(-)
diff --git a/src/common/util.c b/src/common/util.c
index 63a8aff..79e7a70 100644
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -3191,6 +3191,61 @@ tor_join_win_cmdline(const char *argv[])
return joined_argv;
}
+/**
+ * Helper function to output hex numbers, called by
+ * format_helper_exit_status(). This writes the hexadecimal digits of x into
+ * buf, up to max_len digits, and returns the actual number of digits written.
+ * If there is insufficient space, it will write nothing and return 0.
+ *
+ * This accepts an unsigned int because format_helper_exit_status() needs to
+ * call it with a signed int and an unsigned char, and since the C standard
+ * does not guarantee that an int is wider than a char (an int must be at
+ * least 16 bits but it is permitted for a char to be that wide as well), we
+ * can't assume a signed int is sufficient to accomodate an unsigned char.
+ * Thus, format_helper_exit_status() will still need to emit any require '-'
+ * on its own.
+ */
+
+int
+format_hex_number_for_helper_exit_status(unsigned int x, char *buf,
+ int max_len)
+{
+ int len;
+ unsigned int tmp;
+ char *cur;
+
+ /* Sanity check */
+ if (!buf || max_len <= 0)
+ return 0;
+
+ /* How many chars do we need for x? */
+ if (x > 0) {
+ len = 0;
+ tmp = x;
+ while (tmp > 0) {
+ tmp >>= 4;
+ ++len;
+ }
+ }
+ else len = 1;
+
+ /* Bail if we would go past the end of the buffer */
+ if (len > max_len)
+ return 0;
+
+ /* Point to last one */
+ cur = buf + len - 1;
+
+ /* Convert x to hex */
+ do {
+ *cur-- = "0123456789ABCDEF"[x & 0xf];
+ x >>= 4;
+ } while (x != 0 && cur >= buf);
+
+ /* Return len */
+ return len;
+}
+
/** Format <b>child_state</b> and <b>saved_errno</b> as a hex string placed in
* <b>hex_errno</b>. Called between fork and _exit, so must be signal-handler
* safe.
@@ -3208,9 +3263,9 @@ void
format_helper_exit_status(unsigned char child_state, int saved_errno,
char *hex_errno)
{
- unsigned int unsigned_errno, len, tmp_uint;
- char *cur, *tmp;
- unsigned char tmp_uchar;
+ unsigned int unsigned_errno;
+ int written, left;
+ char *cur;
size_t i;
/* Fill hex_errno with spaces, and a trailing newline (memset may
@@ -3226,87 +3281,72 @@ format_helper_exit_status(unsigned char child_state, int saved_errno,
unsigned_errno = (unsigned int) saved_errno;
}
- /* How many chars do we need for child_state ? */
- if ( child_state > 0 ) {
- len = 0;
- tmp_uchar = child_state;
- while (tmp_uchar > 0) {
- tmp_uchar >>= 4;
- ++len;
- }
- }
- else len = 1;
+ /*
+ * Count how many chars of space we have left, and keep a pointer into the
+ * current point in the buffer.
+ */
+ left = HEX_ERRNO_SIZE;
+ cur = hex_errno;
- /* Bail if we would go past the end (on this or the '/') */
- if ( len + 2 > HEX_ERRNO_SIZE)
+ /* Emit child_state */
+ written = format_hex_number_for_helper_exit_status(child_state,
+ cur, left);
+ if (written <= 0)
goto err;
- /* Point to last one */
- cur = hex_errno + len - 1;
-
- /* Convert child_state to hex */
- do {
- *cur-- = "0123456789ABCDEF"[child_state & 0xf];
- child_state >>= 4;
- } while (child_state != 0 && cur >= hex_errno);
-
- /* Check for overflow on first iteration of the loop */
- if (cur + 1 < hex_errno)
+ /* Adjust left and cur */
+ left -= written;
+ cur += written;
+ if (left <= 0)
goto err;
/* Now the '/' */
- hex_errno[len] = '/';
-
- /* Save a pointer to the start of second number */
- tmp = hex_errno + len;
+ *cur = '/';
- /* How many chars do we need for unsigned_errno? */
- if ( unsigned_errno > 0 ) {
- len = 0;
- tmp_uint = unsigned_errno;
- while (tmp_uint > 0) {
- tmp_uint >>= 4;
- ++len;
- }
- }
- else len = 1;
+ /* Adjust left and cur */
+ ++cur;
+ --left;
+ if (left <= 0)
+ goto err;
/* Need minus? */
if (saved_errno < 0) {
- if ( tmp + 1 - hex_errno > (ptrdiff_t)(HEX_ERRNO_SIZE) )
+ *cur = '-';
+ ++cur;
+ --left;
+ if (left <= 0)
goto err;
-
- *(++tmp) = '-';
}
- /* Last check for space */
- if ( tmp + len + 2 - hex_errno > (ptrdiff_t)(HEX_ERRNO_SIZE) )
+ /* Emit unsigned_errno */
+ written = format_hex_number_for_helper_exit_status(unsigned_errno,
+ cur, left);
+
+ if (written <= 0)
goto err;
- /* Point to last one */
- cur = tmp + len;
+ /* Adjust left and cur */
+ left -= written;
+ cur += written;
- /* Convert unsigned_errno to hex */
- do {
- *cur-- = "0123456789ABCDEF"[unsigned_errno & 0xf];
- unsigned_errno >>= 4;
- } while (unsigned_errno != 0 && cur >= tmp);
+ /* Check that we have enough space left for a newline */
+ if (left <= 0)
+ goto err;
/* Emit the newline and NUL */
- cur = tmp + len;
- *(++cur) = '\n';
- *(++cur) = '\0';
+ *cur++ = '\n';
+ *cur++ = '\0';
goto done;
-err:
+ err:
/*
* In error exit, just write a '\0' in the first char so whatever called
* this at least won't fall off the end.
*/
*hex_errno = '\0';
-done:
+ done:
return;
}
diff --git a/src/common/util.h b/src/common/util.h
index a2b196c..6b7c6fb 100644
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -471,6 +471,8 @@ void tor_process_handle_destroy(process_handle_t *process_handle,
#ifdef UTIL_PRIVATE
/* Prototypes for private functions only used by util.c (and unit tests) */
+int format_hex_number_for_helper_exit_status(unsigned int x, char *buf,
+ int max_len);
void format_helper_exit_status(unsigned char child_state,
int saved_errno, char *hex_errno);
_______________________________________________
tor-commits mailing list
tor-commits@xxxxxxxxxxxxxxxxxxxx
https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-commits