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comparison Python/mysnprintf.c @ 61467:f197407bdba2 3.1

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Recorded merge of revisions 81032 via svnmerge from svn+ssh://pythondev@svn.python.org/python/branches/py3k ................ r81032 | antoine.pitrou | 2010-05-09 17:52:27 +0200 (dim., 09 mai 2010) | 9 lines Recorded merge of revisions 81029 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r81029 | antoine.pitrou | 2010-05-09 16:46:46 +0200 (dim., 09 mai 2010) | 3 lines Untabify C files. Will watch buildbots. ........ ................
author Antoine Pitrou <solipsis@pitrou.net>
date Sun, 09 May 2010 16:14:21 +0000
parents ae5f5156b882
children
comparison
equal deleted inserted replaced
61459:f8c19c5f5dd2 61467:f197407bdba2
17 avoid truncation exceeds size by more than 512, Python aborts with a 17 avoid truncation exceeds size by more than 512, Python aborts with a
18 Py_FatalError. 18 Py_FatalError.
19 19
20 Return value (rv): 20 Return value (rv):
21 21
22 When 0 <= rv < size, the output conversion was unexceptional, and 22 When 0 <= rv < size, the output conversion was unexceptional, and
23 rv characters were written to str (excluding a trailing \0 byte at 23 rv characters were written to str (excluding a trailing \0 byte at
24 str[rv]). 24 str[rv]).
25 25
26 When rv >= size, output conversion was truncated, and a buffer of 26 When rv >= size, output conversion was truncated, and a buffer of
27 size rv+1 would have been needed to avoid truncation. str[size-1] 27 size rv+1 would have been needed to avoid truncation. str[size-1]
28 is \0 in this case. 28 is \0 in this case.
29 29
30 When rv < 0, "something bad happened". str[size-1] is \0 in this 30 When rv < 0, "something bad happened". str[size-1] is \0 in this
31 case too, but the rest of str is unreliable. It could be that 31 case too, but the rest of str is unreliable. It could be that
32 an error in format codes was detected by libc, or on platforms 32 an error in format codes was detected by libc, or on platforms
33 with a non-C99 vsnprintf simply that the buffer wasn't big enough 33 with a non-C99 vsnprintf simply that the buffer wasn't big enough
34 to avoid truncation, or on platforms without any vsnprintf that 34 to avoid truncation, or on platforms without any vsnprintf that
35 PyMem_Malloc couldn't obtain space for a temp buffer. 35 PyMem_Malloc couldn't obtain space for a temp buffer.
36 36
37 CAUTION: Unlike C99, str != NULL and size > 0 are required. 37 CAUTION: Unlike C99, str != NULL and size > 0 are required.
38 */ 38 */
39 39
40 int 40 int
41 PyOS_snprintf(char *str, size_t size, const char *format, ...) 41 PyOS_snprintf(char *str, size_t size, const char *format, ...)
42 { 42 {
43 int rc; 43 int rc;
44 va_list va; 44 va_list va;
45 45
46 va_start(va, format); 46 va_start(va, format);
47 rc = PyOS_vsnprintf(str, size, format, va); 47 rc = PyOS_vsnprintf(str, size, format, va);
48 va_end(va); 48 va_end(va);
49 return rc; 49 return rc;
50 } 50 }
51 51
52 int 52 int
53 PyOS_vsnprintf(char *str, size_t size, const char *format, va_list va) 53 PyOS_vsnprintf(char *str, size_t size, const char *format, va_list va)
54 { 54 {
55 int len; /* # bytes written, excluding \0 */ 55 int len; /* # bytes written, excluding \0 */
56 #ifdef HAVE_SNPRINTF 56 #ifdef HAVE_SNPRINTF
57 #define _PyOS_vsnprintf_EXTRA_SPACE 1 57 #define _PyOS_vsnprintf_EXTRA_SPACE 1
58 #else 58 #else
59 #define _PyOS_vsnprintf_EXTRA_SPACE 512 59 #define _PyOS_vsnprintf_EXTRA_SPACE 512
60 char *buffer; 60 char *buffer;
61 #endif 61 #endif
62 assert(str != NULL); 62 assert(str != NULL);
63 assert(size > 0); 63 assert(size > 0);
64 assert(format != NULL); 64 assert(format != NULL);
65 /* We take a size_t as input but return an int. Sanity check 65 /* We take a size_t as input but return an int. Sanity check
66 * our input so that it won't cause an overflow in the 66 * our input so that it won't cause an overflow in the
67 * vsnprintf return value or the buffer malloc size. */ 67 * vsnprintf return value or the buffer malloc size. */
68 if (size > INT_MAX - _PyOS_vsnprintf_EXTRA_SPACE) { 68 if (size > INT_MAX - _PyOS_vsnprintf_EXTRA_SPACE) {
69 len = -666; 69 len = -666;
70 goto Done; 70 goto Done;
71 } 71 }
72 72
73 #ifdef HAVE_SNPRINTF 73 #ifdef HAVE_SNPRINTF
74 len = vsnprintf(str, size, format, va); 74 len = vsnprintf(str, size, format, va);
75 #else 75 #else
76 /* Emulate it. */ 76 /* Emulate it. */
77 buffer = PyMem_MALLOC(size + _PyOS_vsnprintf_EXTRA_SPACE); 77 buffer = PyMem_MALLOC(size + _PyOS_vsnprintf_EXTRA_SPACE);
78 if (buffer == NULL) { 78 if (buffer == NULL) {
79 len = -666; 79 len = -666;
80 goto Done; 80 goto Done;
81 } 81 }
82 82
83 len = vsprintf(buffer, format, va); 83 len = vsprintf(buffer, format, va);
84 if (len < 0) 84 if (len < 0)
85 /* ignore the error */; 85 /* ignore the error */;
86 86
87 else if ((size_t)len >= size + _PyOS_vsnprintf_EXTRA_SPACE) 87 else if ((size_t)len >= size + _PyOS_vsnprintf_EXTRA_SPACE)
88 Py_FatalError("Buffer overflow in PyOS_snprintf/PyOS_vsnprintf"); 88 Py_FatalError("Buffer overflow in PyOS_snprintf/PyOS_vsnprintf");
89 89
90 else { 90 else {
91 const size_t to_copy = (size_t)len < size ? 91 const size_t to_copy = (size_t)len < size ?
92 (size_t)len : size - 1; 92 (size_t)len : size - 1;
93 assert(to_copy < size); 93 assert(to_copy < size);
94 memcpy(str, buffer, to_copy); 94 memcpy(str, buffer, to_copy);
95 str[to_copy] = '\0'; 95 str[to_copy] = '\0';
96 } 96 }
97 PyMem_FREE(buffer); 97 PyMem_FREE(buffer);
98 #endif 98 #endif
99 Done: 99 Done:
100 if (size > 0) 100 if (size > 0)
101 str[size-1] = '\0'; 101 str[size-1] = '\0';
102 return len; 102 return len;
103 #undef _PyOS_vsnprintf_EXTRA_SPACE 103 #undef _PyOS_vsnprintf_EXTRA_SPACE
104 } 104 }