a version of strings(1) that isn’t dependent on a linker. Dumps all strings of any given file.
Based off code provided by toybox
Last active
October 8, 2023 19:23
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a version of `strings(1)` that isn’t dependent on a linker
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| TARGET := strings | |
| SRC := src/strings.c | |
| all: $(TARGET) | |
| $(TARGET): $(SRC) | |
| $(CC) $(LDFLAGS) $^ -o $@ | |
| clean: | |
| $(RM) $(TARGET) |
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| // from https://github.com/landley/toybox/blob/master/toys/posix/strings.c | |
| #include <stdio.h> | |
| #include <stdlib.h> | |
| #include <unistd.h> | |
| #include <fcntl.h> | |
| #define BUFSIZE 4096 | |
| long n = 4; | |
| char buf[BUFSIZE]; | |
| void do_strings(char *filename) { | |
| int fd = open(filename, O_RDONLY); | |
| if (fd < 0) { | |
| perror(filename); | |
| exit(EXIT_FAILURE); | |
| } | |
| int nread, i, wlen = n, count = 0; | |
| off_t offset = 0; | |
| char *string = 0; | |
| string = calloc(wlen+1, sizeof(char)); | |
| if (!string) { | |
| perror("calloc"); | |
| exit(EXIT_FAILURE); | |
| } | |
| for (i = nread = 0; ;i++) { | |
| if (i >= nread) { | |
| nread = read(fd, buf, sizeof(buf)); | |
| i = 0; | |
| if (nread < 0) { | |
| perror(filename); | |
| exit(EXIT_FAILURE); | |
| } | |
| if (nread < 1) { | |
| if (count) goto flush; | |
| break; | |
| } | |
| } | |
| offset++; | |
| if ((buf[i]>=32 && buf[i]<=126) || buf[i]=='\t') { | |
| if (count == wlen) fputc(buf[i], stdout); | |
| else { | |
| string[count++] = buf[i]; | |
| if (count == wlen) { | |
| printf("%s", string); | |
| } | |
| } | |
| continue; | |
| } | |
| flush: | |
| if (count == wlen) putchar('\n'); | |
| count = 0; | |
| } | |
| close(fd); | |
| free(string); | |
| } | |
| int main(int argc, char *argv[]) { | |
| if (argc < 2) { | |
| fprintf(stderr, "Usage: %s [file ...]\n", argv[0]); | |
| exit(EXIT_FAILURE); | |
| } | |
| for (int i = 1; i < argc; i++) { | |
| do_strings(argv[i]); | |
| } | |
| return 0; | |
| } |
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