From 7427406580e78666fad3634b4bfaf1922d4bb457 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Tue, 22 Oct 2019 14:25:43 +0200 Subject: shell: better comments in BASE#nn code function old new delta evaluate_string 932 930 -2 Signed-off-by: Denys Vlasenko --- shell/math.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) (limited to 'shell/math.c') diff --git a/shell/math.c b/shell/math.c index af1ab55c0..aac5017d0 100644 --- a/shell/math.c +++ b/shell/math.c @@ -537,25 +537,23 @@ static arith_t strto_arith_t(const char *nptr, char **endptr) base = (unsigned)n; n = 0; nptr = *endptr + 1; - /* bash allows "N#" (empty "nnnn" part) */ for (;;) { unsigned digit = (unsigned)*nptr - '0'; - if (digit >= 10) { - /* *nptr is not 0..9 */ - if (*nptr > 'z') - break; /* this rejects e.g. $((64#~)) */ + if (digit >= 10 /* not 0..9 */ + && digit <= 'z' - '0' /* needed to reject e.g. $((64#~)) */ + ) { /* in bases up to 36, case does not matter for a-z */ digit = (unsigned)(*nptr | 0x20) - ('a' - 10); if (base > 36 && *nptr <= '_') { - /* otherwise, A-Z,@,_ are 36..61,62,63 */ - if (*nptr == '@') - digit = 62; - else if (*nptr == '_') + /* otherwise, A-Z,@,_ are 36-61,62,63 */ + if (*nptr == '_') digit = 63; + else if (*nptr == '@') + digit = 62; else if (digit < 36) /* A-Z */ digit += 36 - 10; else - break; /* error, such as [ or \ */ + break; /* error: one of [\]^ */ } //bb_error_msg("ch:'%c'%d digit:%u", *nptr, *nptr, digit); //if (digit < 10) - example where we need this? @@ -567,6 +565,12 @@ static arith_t strto_arith_t(const char *nptr, char **endptr) n = n * base + digit; nptr++; } + /* Note: we do not set errno on bad chars, we just set a pointer + * to the first invalid char. For example, this allows + * "N#" (empty "nnnn" part): 64#+1 is a valid expression, + * it means 64# + 1, whereas 64#~... is not, since ~ is not a valid + * operator. + */ *endptr = (char*)nptr; return n; } -- cgit v1.2.3