bitvec_read_field(): indicate errors using errno
This function returns an *unsigned* integer (uint64_t), so returning
a negative value on error is a bad idea. A negative value turns into
a huge positive value, what was demonstrated in the bitvec_test:
bitvec_read_field(idx=512, len=16) => ffffffffffffffea
bitvec_read_field(idx=0, len=65) => ffffffffffffffea
bitvec_read_field(idx=64, len=16) => ffffffffffffffea
The 0xffffffffffffffea above is basically:
(uint64_t) -EINVAL, or
(uint64_t) -22 + 1, or
0xffffffffffffffff - 0x16 + 1.
Let's make use of the errno in order to indicate an error to the caller.
Change-Id: I2cc734caa3365d03c2ae2b3f2cd9544933c25e9e
Related: OS#4388
diff --git a/src/bitvec.c b/src/bitvec.c
index 2b4e8c9..b411a72 100644
--- a/src/bitvec.c
+++ b/src/bitvec.c
@@ -472,18 +472,23 @@
* \param[in] bv The boolean vector to work on
* \param[in,out] read_index Where reading supposed to start in the vector
* \param[in] len How many bits to read from vector
- * \returns read bits or negative value on error
+ * \returns An integer made up of the bits read.
+ *
+ * In case of an error, errno is set to a non-zero value. Otherwise it holds 0.
*/
uint64_t bitvec_read_field(struct bitvec *bv, unsigned int *read_index, unsigned int len)
{
unsigned int i;
uint64_t ui = 0;
bv->cur_bit = *read_index;
+ errno = 0;
for (i = 0; i < len; i++) {
int bit = bitvec_get_bit_pos((const struct bitvec *)bv, bv->cur_bit);
- if (bit < 0)
- return bit;
+ if (bit < 0) {
+ errno = -bit;
+ break;
+ }
if (bit)
ui |= ((uint64_t)1 << (len - i - 1));
bv->cur_bit++;
diff --git a/tests/bitvec/bitvec_test.c b/tests/bitvec/bitvec_test.c
index b4764e6..ea7ea9a 100644
--- a/tests/bitvec/bitvec_test.c
+++ b/tests/bitvec/bitvec_test.c
@@ -237,7 +237,8 @@
#define _bitvec_read_field(idx, len) \
readIndex = idx; \
field = bitvec_read_field(&bv, &readIndex, len); \
- printf("bitvec_read_field(idx=%u, len=%u) => %" PRIx64 "\n", idx, len, field);
+ printf("bitvec_read_field(idx=%u, len=%u) => %" PRIx64 " (%s)\n", \
+ idx, len, field, errno == 0 ? "success" : "error");
_bitvec_read_field(0, 64);
_bitvec_read_field(0, 32);
diff --git a/tests/bitvec/bitvec_test.ok b/tests/bitvec/bitvec_test.ok
index b118502..a0e31d3 100644
--- a/tests/bitvec/bitvec_test.ok
+++ b/tests/bitvec/bitvec_test.ok
@@ -171,21 +171,21 @@
bitvec bytes used.
test bitvec_read_field():
-bitvec_read_field(idx=0, len=64) => deadbeeffeebdaed
-bitvec_read_field(idx=0, len=32) => deadbeef
-bitvec_read_field(idx=0, len=16) => dead
-bitvec_read_field(idx=0, len=8) => de
-bitvec_read_field(idx=0, len=0) => 0
-bitvec_read_field(idx=8, len=8) => ad
-bitvec_read_field(idx=8, len=4) => a
-bitvec_read_field(idx=8, len=0) => 0
-bitvec_read_field(idx=10, len=9) => 16d
-bitvec_read_field(idx=10, len=7) => 5b
-bitvec_read_field(idx=10, len=5) => 16
-bitvec_read_field(idx=10, len=3) => 5
-bitvec_read_field(idx=10, len=1) => 1
-bitvec_read_field(idx=512, len=16) => ffffffffffffffea
-bitvec_read_field(idx=0, len=65) => ffffffffffffffea
-bitvec_read_field(idx=64, len=16) => ffffffffffffffea
+bitvec_read_field(idx=0, len=64) => deadbeeffeebdaed (success)
+bitvec_read_field(idx=0, len=32) => deadbeef (success)
+bitvec_read_field(idx=0, len=16) => dead (success)
+bitvec_read_field(idx=0, len=8) => de (success)
+bitvec_read_field(idx=0, len=0) => 0 (success)
+bitvec_read_field(idx=8, len=8) => ad (success)
+bitvec_read_field(idx=8, len=4) => a (success)
+bitvec_read_field(idx=8, len=0) => 0 (success)
+bitvec_read_field(idx=10, len=9) => 16d (success)
+bitvec_read_field(idx=10, len=7) => 5b (success)
+bitvec_read_field(idx=10, len=5) => 16 (success)
+bitvec_read_field(idx=10, len=3) => 5 (success)
+bitvec_read_field(idx=10, len=1) => 1 (success)
+bitvec_read_field(idx=512, len=16) => 0 (error)
+bitvec_read_field(idx=0, len=65) => bd5b7ddffdd7b5db (error)
+bitvec_read_field(idx=64, len=16) => 0 (error)
bitvec ok.