Line | Count | Source (jump to first uncovered line) |
1 | #include "Python.h" |
2 | |
3 | /* snprintf() and vsnprintf() wrappers. |
4 | |
5 | If the platform has vsnprintf, we use it, else we |
6 | emulate it in a half-hearted way. Even if the platform has it, we wrap |
7 | it because platforms differ in what vsnprintf does in case the buffer |
8 | is too small: C99 behavior is to return the number of characters that |
9 | would have been written had the buffer not been too small, and to set |
10 | the last byte of the buffer to \0. At least MS _vsnprintf returns a |
11 | negative value instead, and fills the entire buffer with non-\0 data. |
12 | |
13 | The wrappers ensure that str[size-1] is always \0 upon return. |
14 | |
15 | PyOS_snprintf and PyOS_vsnprintf never write more than size bytes |
16 | (including the trailing '\0') into str. |
17 | |
18 | Return value (rv): |
19 | |
20 | When 0 <= rv < size, the output conversion was unexceptional, and |
21 | rv characters were written to str (excluding a trailing \0 byte at |
22 | str[rv]). |
23 | |
24 | When rv >= size, output conversion was truncated, and a buffer of |
25 | size rv+1 would have been needed to avoid truncation. str[size-1] |
26 | is \0 in this case. |
27 | |
28 | When rv < 0, "something bad happened". str[size-1] is \0 in this |
29 | case too, but the rest of str is unreliable. It could be that |
30 | an error in format codes was detected by libc, or on platforms |
31 | with a non-C99 vsnprintf simply that the buffer wasn't big enough |
32 | to avoid truncation, or on platforms without any vsnprintf that |
33 | PyMem_Malloc couldn't obtain space for a temp buffer. |
34 | |
35 | CAUTION: Unlike C99, str != NULL and size > 0 are required. |
36 | Also, size must be smaller than INT_MAX. |
37 | */ |
38 | |
39 | int |
40 | PyOS_snprintf(char *str, size_t size, const char *format, ...) |
41 | { |
42 | int rc; |
43 | va_list va; |
44 | |
45 | va_start(va, format); |
46 | rc = PyOS_vsnprintf(str, size, format, va); |
47 | va_end(va); |
48 | return rc; |
49 | } |
50 | |
51 | int |
52 | PyOS_vsnprintf(char *str, size_t size, const char *format, va_list va) |
53 | { |
54 | assert(str != NULL); |
55 | assert(size > 0); |
56 | assert(size <= (INT_MAX - 1)); |
57 | assert(format != NULL); |
58 | |
59 | int len; /* # bytes written, excluding \0 */ |
60 | /* We take a size_t as input but return an int. Sanity check |
61 | * our input so that it won't cause an overflow in the |
62 | * vsnprintf return value. */ |
63 | if (size > INT_MAX - 1) { Branch (63:9): [True: 0, False: 1.33M]
|
64 | len = -666; |
65 | goto Done; |
66 | } |
67 | |
68 | #if defined(_MSC_VER) |
69 | len = _vsnprintf(str, size, format, va); |
70 | #else |
71 | len = vsnprintf(str, size, format, va); |
72 | #endif |
73 | |
74 | Done: |
75 | if (size > 0) { Branch (75:9): [True: 1.33M, False: 0]
|
76 | str[size-1] = '\0'; |
77 | } |
78 | return len; |
79 | } |