742740658
Denys Vlasenko
2019-10-22
Subject
shell: better comments in BASE#nn code
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shell/math.c+14 -10
| @@ -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; | |
| } | |