diff options
| -rw-r--r-- | shell/ash.c | 71 |
1 files changed, 59 insertions, 12 deletions
diff --git a/shell/ash.c b/shell/ash.c index 0a8b6c0f2..ce82a965c 100644 --- a/shell/ash.c +++ b/shell/ash.c @@ -6040,25 +6040,61 @@ scanleft(char *startp, char *rmesc, char *rmescend UNUSED_PARAM, char *str, int } static char * -scanright(char *startp, char *rmesc, char *rmescend, char *str, int quotes, - int zero) +scanright(char *startp, char *rmesc, char *rmescend, char *pattern, int quotes, int match_at_start) { +#if !ENABLE_ASH_OPTIMIZE_FOR_SIZE + int try2optimize = match_at_start; +#endif int esc = 0; char *loc; char *loc2; - for (loc = str - 1, loc2 = rmescend; loc >= startp; loc2--) { + /* If we called by "${v/pattern/repl}" or "${v//pattern/repl}": + * startp="escaped_value_of_v" rmesc="raw_value_of_v" + * rmescend=""(ptr to NUL in rmesc) pattern="pattern" quotes=match_at_start=1 + * Logic: + * loc starts at NUL at the end of startp, loc2 starts at the end of rmesc, + * and on each iteration they go back two/one char until they reach the beginning. + * We try to find a match in "raw_value_of_v", "raw_value_of_", "raw_value_of" etc. + */ + /* TODO: document in what other circumstances we are called. */ + + for (loc = pattern - 1, loc2 = rmescend; loc >= startp; loc2--) { int match; char c = *loc2; const char *s = loc2; - if (zero) { + if (match_at_start) { *loc2 = '\0'; s = rmesc; } - match = pmatch(str, s); + match = pmatch(pattern, s); + //bb_error_msg("pmatch(pattern:'%s',s:'%s'):%d", pattern, s, match); *loc2 = c; if (match) return loc; +#if !ENABLE_ASH_OPTIMIZE_FOR_SIZE + if (try2optimize) { + /* Maybe we can optimize this: + * if pattern ends with unescaped *, we can avoid checking + * shorter strings: if "foo*" doesnt match "raw_value_of_v", + * it wont match truncated "raw_value_of_" strings too. + */ + unsigned plen = strlen(pattern); + /* Does it end with "*"? */ + if (plen != 0 && pattern[--plen] == '*') { + /* "xxxx*" is not escaped */ + /* "xxx\*" is escaped */ + /* "xx\\*" is not escaped */ + /* "x\\\*" is escaped */ + int slashes = 0; + while (plen != 0 && pattern[--plen] == '\\') + slashes++; + if (!(slashes & 1)) + break; /* ends with unescaped "*" */ + } + try2optimize = 0; + } +#endif loc--; if (quotes) { if (--esc < 0) { @@ -6248,7 +6284,7 @@ subevalvar(char *p, char *str, int strloc, int subtype, #if ENABLE_ASH_BASH_COMPAT if (subtype == VSREPLACE || subtype == VSREPLACEALL) { - char *idx, *end, *restart_detect; + char *idx, *end; if (!repl) { repl = parse_sub_pattern(str, varflags & VSQUOTE); @@ -6257,17 +6293,19 @@ subevalvar(char *p, char *str, int strloc, int subtype, } /* If there's no pattern to match, return the expansion unmolested */ - if (*str == '\0') + if (str[0] == '\0') return 0; len = 0; idx = startp; end = str - 1; while (idx < end) { + try_to_match: loc = scanright(idx, rmesc, rmescend, str, quotes, 1); if (!loc) { /* No match, advance */ - restart_detect = stackblock(); + char *restart_detect = stackblock(); + skip_matching: STPUTC(*idx, expdest); if (quotes && (unsigned char)*idx == CTLESC) { idx++; @@ -6279,7 +6317,16 @@ subevalvar(char *p, char *str, int strloc, int subtype, idx++; len++; rmesc++; - continue; + /* continue; - prone to quadratic behavior, smarter code: */ + if (idx >= end) + break; + if (str[0] == '*') { + /* Pattern is "*foo". If "*foo" does not match "long_string", + * it would never match "ong_string" etc, no point in trying. + */ + goto skip_matching; + } + goto try_to_match; } if (subtype == VSREPLACEALL) { @@ -6294,7 +6341,7 @@ subevalvar(char *p, char *str, int strloc, int subtype, } for (loc = repl; *loc; loc++) { - restart_detect = stackblock(); + char *restart_detect = stackblock(); STPUTC(*loc, expdest); if (stackblock() != restart_detect) goto restart; @@ -6303,7 +6350,7 @@ subevalvar(char *p, char *str, int strloc, int subtype, if (subtype == VSREPLACE) { while (*idx) { - restart_detect = stackblock(); + char *restart_detect = stackblock(); STPUTC(*idx, expdest); if (stackblock() != restart_detect) goto restart; @@ -6332,7 +6379,7 @@ subevalvar(char *p, char *str, int strloc, int subtype, if (subtype < 0 || subtype > 7) abort(); #endif - /* zero = subtype == VSTRIMLEFT || subtype == VSTRIMLEFTMAX */ + /* zero = (subtype == VSTRIMLEFT || subtype == VSTRIMLEFTMAX) */ zero = subtype >> 1; /* VSTRIMLEFT/VSTRIMRIGHTMAX -> scanleft */ scan = (subtype & 1) ^ zero ? scanleft : scanright; |