diff options
Diffstat (limited to 'grab.c')
| -rw-r--r-- | grab.c | 274 |
1 files changed, 274 insertions, 0 deletions
@@ -0,0 +1,274 @@ +#include <assert.h> +#include <err.h> +#include <limits.h> +#include <locale.h> +#include <regex.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "da.h" + +#ifndef REG_STARTEND +# error "REG_STARTEND not defined" +#endif + +#define die(...) err(EXIT_FAILURE, __VA_ARGS__); +#define diex(...) errx(EXIT_FAILURE, __VA_ARGS__); + +#define EEARLY "Input string terminated prematurely" + +struct op { + char c; + regex_t pat; +}; + +struct ops { + struct op *buf; + size_t len, cap; +}; + +struct chars { + char *buf; + size_t len, cap; +}; + +struct sv { + char *p; + size_t len; +}; + +typedef unsigned char uchar; +typedef void (*cmd_func)(struct sv, struct ops, size_t); + +static void cmdg(struct sv, struct ops, size_t); +static void cmdx(struct sv, struct ops, size_t); + +static void grab(struct ops, FILE *, const char *); +static void putsv(struct sv); +static regex_t mkregex(char *, size_t); +static struct ops comppat(char *); + +static bool xisspace(char); +static char *xstrchrnul(const char *, char); + +static int rv = EXIT_SUCCESS; +static const char *delim = "\n"; +static const cmd_func op_table[UCHAR_MAX] = { + ['g'] = cmdg, + ['v'] = cmdg, + ['x'] = cmdx, + // ['y'] = cmdy, +}; + +static void +usage(const char *s) +{ + fprintf(stderr, "Usage: %s [-d string] pattern [file ...]\n", s); + exit(EXIT_FAILURE); +} + +int +main(int argc, char **argv) +{ + int rv, opt; + struct ops ops; + + if (argc < 2) + usage(argv[0]); + + setlocale(LC_ALL, ""); + + while ((opt = getopt(argc, argv, "d:")) != -1) { + switch (opt) { + case 'd': + delim = optarg; + break; + default: + usage(argv[0]); + } + } + + argc -= optind; + argv += optind; + + ops = comppat(argv[0]); + if (argc == 1) + grab(ops, stdin, "-"); + else { + for (int i = 1; i < argc; i++) { + FILE *fp; + + if (strcmp(argv[i], "-") == 0) { + grab(ops, stdin, "-"); + } else if ((fp = fopen(argv[i], "r")) == NULL) { + warn("fopen: %s", argv[i]); + rv = EXIT_FAILURE; + } else { + grab(ops, fp, argv[i]); + fclose(fp); + } + } + } + +#ifdef GRAB_DEBUG + for (size_t i = 0; i < ops.len; i++) + regfree(&ops.buf[i].pat); + free(ops.buf); +#endif + + return rv; +} + +struct ops +comppat(char *s) +{ +#define skip_ws(p) for (; *(p) && xisspace(*(p)); (p)++) + struct ops ops; + + da_init(&ops, 8); + skip_ws(s); + if (!*s) + diex(EEARLY); + + do { + char delim; + char *p; + struct op op; + + op.c = *s; + if (!op_table[(uchar)op.c]) + diex("Invalid operator ‘%c’", *s); + if (!(delim = *++s)) + diex(EEARLY); + + p = ++s; + s = xstrchrnul(s, delim); + op.pat = mkregex(p, s - p); + da_append(&ops, op); + + if (*s) + s++; + skip_ws(s); + } while (*s && *(s + 1)); + + return ops; +#undef skip_ws +} + +void +grab(struct ops ops, FILE *stream, const char *filename) +{ + size_t n; + struct chars chars = {0}; + + do { + static_assert(sizeof(char) == 1, "sizeof(char) != 1; wtf?"); + chars.cap += BUFSIZ; + if ((chars.buf = realloc(chars.buf, chars.cap)) == NULL) + die("realloc"); + chars.len += n = fread(chars.buf + chars.len, 1, BUFSIZ, stream); + } while (n == BUFSIZ); + + if (ferror(stream)) { + warn("fread: %s", filename); + rv = EXIT_FAILURE; + } else + cmdx((struct sv){.p = chars.buf, .len = chars.len}, ops, 0); + + free(chars.buf); +} + +void +cmdx(struct sv sv, struct ops ops, size_t i) +{ + regmatch_t pm = { + .rm_so = 0, + .rm_eo = sv.len, + }; + struct op op = ops.buf[i]; + + do { + struct sv nsv; + + if (regexec(&op.pat, sv.p, 1, &pm, REG_STARTEND) == REG_NOMATCH) + break; + nsv = (struct sv){.p = sv.p + pm.rm_so, .len = pm.rm_eo - pm.rm_so}; + if (i + 1 == ops.len) + putsv(nsv); + else + op_table[(uchar)ops.buf[i + 1].c](nsv, ops, i + 1); + + if (pm.rm_so == pm.rm_eo) + pm.rm_eo++; + pm = (regmatch_t){ + .rm_so = pm.rm_eo, + .rm_eo = sv.len, + }; + } while (pm.rm_so < pm.rm_eo); +} + +void +cmdg(struct sv sv, struct ops ops, size_t i) +{ + int r; + regmatch_t pm = { + .rm_so = 0, + .rm_eo = sv.len, + }; + struct op op = ops.buf[i]; + + r = regexec(&op.pat, sv.p, 1, &pm, REG_STARTEND); + if ((r == REG_NOMATCH && op.c == 'g') || (r != REG_NOMATCH && op.c == 'v')) + return; + + if (i + 1 == ops.len) + putsv(sv); + else + op_table[(uchar)ops.buf[i + 1].c](sv, ops, i + 1); +} + +void +putsv(struct sv sv) +{ + fwrite(sv.p, 1, sv.len, stdout); + fputs(delim, stdout); +} + +regex_t +mkregex(char *s, size_t n) +{ + char c = s[n]; + int ret; + regex_t r; + + s[n] = 0; + if ((ret = regcomp(&r, s, REG_EXTENDED | REG_NEWLINE)) != 0) { + char emsg[128]; + regerror(ret, &r, emsg, sizeof(emsg)); + diex("Failed to compile regex: %s", emsg); + } + s[n] = c; + + return r; +} + +bool +xisspace(char c) +{ + return c == ' ' || c == '\t' || c == '\n'; +} + +char * +xstrchrnul(const char *s, char c) +{ + for (; *s; s++) { + if (*s == '\\') + s++; + else if (*s == c) + break; + } + return (char *)s; +} |