The current code implements the 'm' modifier only for 's' conversions and would cause a segfault if it was used for 'c' or '[' conversions. This patch extends the code to cover these cases too.
Signed-off-by: Will Newton <[email protected]> --- libc/stdio/_scanf.c | 51 ++++++++++++++++++++++++++++++++------------------- 1 files changed, 32 insertions(+), 19 deletions(-) diff --git a/libc/stdio/_scanf.c b/libc/stdio/_scanf.c index 952853c..c862afb 100644 --- a/libc/stdio/_scanf.c +++ b/libc/stdio/_scanf.c @@ -1355,7 +1355,21 @@ int VFSCANF (FILE *__restrict fp, const Wchar *__restrict format, va_list arg) (psfs.conv_num >= CONV_c) #endif /* __UCLIBC_HAS_WCHAR__ */ { + /* We might have to handle the allocation ourselves */ + int len; + unsigned char **ptr; + b = (psfs.store ? ((unsigned char *) psfs.cur_ptr) : buf); + /* With 'm', we actually got a pointer to a pointer */ + ptr = (void *)b; + + i = 0; + if (psfs.flags & FLAG_MALLOC) { + len = 0; + b = NULL; + } else + len = -1; + fail = 1; if (psfs.conv_num == CONV_c) { @@ -1363,31 +1377,25 @@ int VFSCANF (FILE *__restrict fp, const Wchar *__restrict format, va_list arg) sc.width = 1; } + if (psfs.flags & FLAG_MALLOC) + b = malloc(sc.width); + while (__scan_getc(&sc) >= 0) { zero_conversions = 0; - *b = sc.cc; - b += psfs.store; + b[i] = sc.cc; + i += psfs.store; } __scan_ungetc(&sc); if (sc.width > 0) { /* Failed to read all required. */ goto DONE; } + if (psfs.flags & FLAG_MALLOC) + *ptr = b; psfs.cnt += psfs.store; goto NEXT_FMT; } if (psfs.conv_num == CONV_s) { - /* We might have to handle the allocation ourselves */ - int len; - /* With 'm', we actually got a pointer to a pointer */ - unsigned char **ptr = (void *)b; - - i = 0; - if (psfs.flags & FLAG_MALLOC) { - len = 0; - b = NULL; - } else - len = -1; /* Yes, believe it or not, a %s conversion can store nuls. */ while ((__scan_getc(&sc) >= 0) && !isspace(sc.cc)) { @@ -1403,10 +1411,6 @@ int VFSCANF (FILE *__restrict fp, const Wchar *__restrict format, va_list arg) fail = 0; } - if (psfs.flags & FLAG_MALLOC) - *ptr = b; - /* The code below takes care of terminating NUL */ - b += i; } else { #ifdef __UCLIBC_HAS_WCHAR__ assert((psfs.conv_num == CONV_LEFTBRACKET) || \ @@ -1462,8 +1466,14 @@ int VFSCANF (FILE *__restrict fp, const Wchar *__restrict format, va_list arg) if (!scanset[sc.cc]) { break; } - *b = sc.cc; - b += psfs.store; + if (i == len) { + /* Pick a size that won't trigger a lot of + * mallocs early on ... */ + len += 256; + b = realloc(b, len + 1); + } + b[i] = sc.cc; + i += psfs.store; fail = 0; } } @@ -1473,6 +1483,9 @@ int VFSCANF (FILE *__restrict fp, const Wchar *__restrict format, va_list arg) if (fail) { /* nothing stored! */ goto DONE; } + if (psfs.flags & FLAG_MALLOC) + *ptr = b; + b += i; *b = 0; /* Nul-terminate string. */ psfs.cnt += psfs.store; goto NEXT_FMT; -- 1.7.1
0001-_scanf.c-Implement-m-modifier-for-c-and-conversions.patch
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