789ccac7d
Denys Vlasenko
2023-12-31
Subject
awk: fix handling of empty fields
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editors/awk.c+17 -16
| @@ -555,8 +555,9 @@ struct globals { | |
| //we are reusing ahash as fdhash, via define (see later) | |
| const char *g_progname; | |
| int g_lineno; | |
| - | int nfields; |
| - | unsigned maxfields; |
| + | int num_fields; /* number of existing $N's */ |
| + | unsigned num_alloc_fields; /* current size of Fields[] */ |
| + | /* NB: Fields[0] corresponds to $1, not to $0 */ |
| var *Fields; | |
| char *g_pos; | |
| char g_saved_ch; | |
| @@ -631,8 +632,8 @@ struct globals2 { | |
| // for fdhash in execution stage. | |
| #define g_progname (G1.g_progname ) | |
| #define g_lineno (G1.g_lineno ) | |
| - | #define nfields (G1.nfields ) |
| - | #define maxfields (G1.maxfields ) |
| + | #define num_fields (G1.num_fields ) |
| + | #define num_alloc_fields (G1.num_alloc_fields) |
| #define Fields (G1.Fields ) | |
| #define g_pos (G1.g_pos ) | |
| #define g_saved_ch (G1.g_saved_ch ) | |
| @@ -1966,30 +1967,30 @@ static void fsrealloc(int size) | |
| { | |
| int i, newsize; | |
| - | if ((unsigned)size >= maxfields) { |
| + | if ((unsigned)size >= num_alloc_fields) { |
| /* Sanity cap, easier than catering for over/underflows */ | |
| if ((unsigned)size > 0xffffff) | |
| bb_die_memory_exhausted(); | |
| - | i = maxfields; |
| - | maxfields = size + 16; |
| + | i = num_alloc_fields; |
| + | num_alloc_fields = size + 16; |
| - | newsize = maxfields * sizeof(Fields[0]); |
| + | newsize = num_alloc_fields * sizeof(Fields[0]); |
| debug_printf_eval("fsrealloc: xrealloc(%p, %u)\n", Fields, newsize); | |
| Fields = xrealloc(Fields, newsize); | |
| debug_printf_eval("fsrealloc: Fields=%p..%p\n", Fields, (char*)Fields + newsize - 1); | |
| /* ^^^ did Fields[] move? debug aid for L.v getting "upstaged" by R.v in evaluate() */ | |
| - | for (; i < maxfields; i++) { |
| - | Fields[i].type = VF_SPECIAL; |
| + | for (; i < num_alloc_fields; i++) { |
| + | Fields[i].type = VF_SPECIAL | VF_DIRTY; |
| Fields[i].string = NULL; | |
| } | |
| } | |
| - | /* if size < nfields, clear extra field variables */ |
| - | for (i = size; i < nfields; i++) { |
| + | /* if size < num_fields, clear extra field variables */ |
| + | for (i = size; i < num_fields; i++) { |
| clrvar(Fields + i); | |
| } | |
| - | nfields = size; |
| + | num_fields = size; |
| } | |
| static int regexec1_nonempty(const regex_t *preg, const char *s, regmatch_t pmatch[]) | |
| @@ -2126,7 +2127,7 @@ static void split_f0(void) | |
| /* set NF manually to avoid side effects */ | |
| clrvar(intvar[NF]); | |
| intvar[NF]->type = VF_NUMBER | VF_SPECIAL; | |
| - | intvar[NF]->number = nfields; |
| + | intvar[NF]->number = num_fields; |
| #undef fstrings | |
| } | |
| @@ -2976,7 +2977,7 @@ static var *evaluate(node *op, var *res) | |
| syntax_error(EMSG_TOO_FEW_ARGS); | |
| L.v = evaluate(op1, TMPVAR0); | |
| /* Does L.v point to $n variable? */ | |
| - | if ((size_t)(L.v - Fields) < maxfields) { |
| + | if ((size_t)(L.v - Fields) < num_alloc_fields) { |
| /* yes, remember where Fields[] is */ | |
| old_Fields_ptr = Fields; | |
| } | |
| @@ -3517,7 +3518,7 @@ static var *evaluate(node *op, var *res) | |
| res = intvar[F0]; | |
| } else { | |
| split_f0(); | |
| - | if (i > nfields) |
| + | if (i > num_fields) |
| fsrealloc(i); | |
| res = &Fields[i - 1]; | |
| } | |
testsuite/awk.tests+7 -0
| @@ -592,6 +592,13 @@ testing 'awk gensub backslashes \\0' \ | |
| \\0|\\0 | |
| ' '' '' | |
| + | # References to empty (not provided in the input) fields in first versus subsequent lines |
| + | testing 'awk references to empty fields' \ |
| + | 'awk '$sq'$2 != 0'$sq \ |
| + | 'a |
| + | b |
| + | ' '' 'a\nb\n' |
| + | |
| # The "b" in "abc" should not match <b* pattern. | |
| # Currently we use REG_STARTEND ("This flag is a BSD extension, not present in POSIX") | |
| # to implement the code to handle this correctly, but if your libc has no REG_STARTEND, | |