From ee68a0baf2f8ec82b758d1dcaf3d71cb5b633b3d Mon Sep 17 00:00:00 2001
From: Thomas Voss <mail@thomasvoss.com>
Date: Sun, 9 Apr 2023 02:37:15 +0200
Subject: Add the source code

---
 fsub.c | 181 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 181 insertions(+)
 create mode 100644 fsub.c

diff --git a/fsub.c b/fsub.c
new file mode 100644
index 0000000..4bc394f
--- /dev/null
+++ b/fsub.c
@@ -0,0 +1,181 @@
+/*
+ * BSD Zero Clause License
+ *
+ * Copyright (c) 2023 Thomas Voss
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#define PCRE2_CODE_UNIT_WIDTH 8
+#define _POSIX_C_SOURCE 200809L
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#include <err.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <pcre2.h>
+
+#define die(...)    err(EXIT_FAILURE, __VA_ARGS__)
+#define streq(a, b) (strcmp(a, b) == 0)
+
+int rv = EXIT_SUCCESS;
+const char *argv0;
+static PCRE2_UCHAR errbuf[256];
+
+static int   loadfile(char **, char *);
+static char *stdio_to_string(void);
+static void  fsub(char *, pcre2_match_data *, pcre2_code *, char *);
+
+int
+main(int argc, char *argv[])
+{
+	int fd, fd2, ec, opt;
+	char *needle, *haystack, *repl,
+	     *argv0 = argv[0],
+	     *optstr = "dim",
+	     *progargs = "[-dim] pattern file [file ...]";
+	uint32_t rx_opts = PCRE2_UTF;
+	pcre2_code *rx;
+	pcre2_match_data *mdata;
+	PCRE2_SIZE eo;
+	static struct option longopts[] = {
+		{"dotall",      no_argument, NULL, 'd'},
+		{"ignore-case", no_argument, NULL, 'i'},
+		{"multiline",   no_argument, NULL, 'm'},
+		{ NULL,         0,           NULL,  0 }
+	};
+
+	argv0 = argv[0];
+	while ((opt = getopt_long(argc, argv, optstr, longopts, NULL)) != -1) {
+		switch (opt) {
+		case 'd':
+			rx_opts |= PCRE2_DOTALL;
+			break;
+		case 'i':
+			rx_opts |= PCRE2_CASELESS;
+			break;
+		case 'm':
+			rx_opts |= PCRE2_MULTILINE;
+			break;
+		default:
+			fprintf(stderr, "Usage: %s %s\n", argv0, progargs);
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	argc -= optind;
+	argv += optind;
+
+	if (argc < 2) {
+		fprintf(stderr, "Usage: %s %s\n", argv0, progargs);
+		exit(EXIT_FAILURE);
+	}
+
+	needle = argv[0];
+	fd = loadfile(&repl, argv[1]);
+	rx = pcre2_compile((PCRE2_SPTR) needle, PCRE2_ZERO_TERMINATED,
+	                   rx_opts, &ec, &eo, NULL);
+	if (rx == NULL) {
+		pcre2_get_error_message(ec, errbuf, sizeof(errbuf));
+		fprintf(stderr,
+		        "%s: Regex compilation failed at offset %d: %s\n",
+		        argv[0], (int) eo, errbuf);
+		exit(EXIT_FAILURE);
+	}
+	mdata = pcre2_match_data_create_from_pattern(rx, NULL);
+
+	for (int i = 2; i < argc; i++) {
+		if (streq(argv[i], "-")) {
+			haystack = stdio_to_string();
+			fsub(haystack, mdata, rx, repl);
+			free(haystack);
+		} else {
+			fd2 = loadfile(&haystack, argv[i]);
+			fsub(haystack, mdata, rx, repl);
+			close(fd2);
+		}
+	}
+
+	pcre2_match_data_free(mdata);
+	pcre2_code_free(rx);
+	close(fd);
+
+	return rv;
+}
+
+int
+loadfile(char **s, char *filename)
+{
+	int fd;
+	struct stat sb;
+
+	if ((fd = open(filename, O_RDONLY)) == -1)
+		die("open: %s", filename);
+	if (fstat(fd, &sb) == -1)
+		die("fstat: %s", filename);
+	*s = mmap(0, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	if (*s == MAP_FAILED)
+		die("mmap: %s", filename);
+	return fd;
+}
+
+char *
+stdio_to_string(void)
+{
+	char *buf = NULL;
+	size_t bs = 0;
+
+	getdelim(&buf, &bs, EOF, stdin);
+
+	return buf;
+}
+
+void
+fsub(char *haystack, pcre2_match_data *mdata, pcre2_code *rx, char *repl)
+{
+	int rc;
+	size_t pos = 0;
+	PCRE2_SPTR haystack_start = (PCRE2_SPTR) haystack;
+	PCRE2_SIZE *ovec;
+	(void) repl;
+
+	do {
+		rc = pcre2_match(rx, haystack_start, PCRE2_ZERO_TERMINATED, pos,
+		                 0, mdata, NULL);
+		if (rc == PCRE2_ERROR_NOMATCH) {
+			if (pos == 0)
+				rv = EXIT_FAILURE;
+			break;
+		}
+		if (rc < 0) {
+			fprintf(stderr,
+			        "%s: pcre2_match() failed with code %d\n",
+			        argv0, rc);
+			pcre2_match_data_free(mdata);
+			pcre2_code_free(rx);
+			exit(EXIT_FAILURE);
+		}
+		ovec = pcre2_get_ovector_pointer(mdata);
+		printf("%.*s%s", (int) (ovec[0] - pos), haystack_start + pos,
+		       repl);
+		pos = ovec[1];
+	} while (rc >= 0);
+	fputs((char *) haystack_start + pos, stdout);
+}
-- 
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