Enrico Fraccaroli (Galfurian)
86 lines
2.5 KiB
C
86 lines
2.5 KiB
C
/// @file cat.c
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/// @brief `cat` program.
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/// @copyright (c) 2014-2024 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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#include "io/debug.h"
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#include "stddef.h"
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/unistd.h>
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#include <strerror.h>
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#include <sys/stat.h>
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int main(int argc, char **argv)
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{
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if (argc < 2) {
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printf("cat: missing operand.\n");
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printf("Try 'cat --help' for more information.\n\n");
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return 1;
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}
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// Check if `--help` is provided.
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for (int i = 1; i < argc; ++i) {
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if ((strcmp(argv[i], "--help") == 0) || (strcmp(argv[i], "-h") == 0)) {
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printf("Prints the content of the given file.\n");
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printf("Usage:\n");
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printf(" cat <file>\n\n");
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return 0;
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}
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}
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int fd;
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// Prepare the buffer for reading.
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char buffer[BUFSIZ];
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// Iterate the arguments.
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for (int i = 1; i < argc; ++i) {
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// Create the stat buffer.
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stat_t statbuf;
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// Initialize the file path.
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char *filepath = argv[i];
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// Stat the file.
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if (stat(argv[i], &statbuf) == -1) {
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printf("cat: %s: %s\n\n", argv[i], strerror(errno));
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continue;
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}
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// Check if it is a link.
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if (S_ISLNK(statbuf.st_mode)) {
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// Read the content of the link.
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if (readlink(filepath, buffer, BUFSIZ) < 0) {
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printf("cat: %s: %s\n\n", filepath, strerror(errno));
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continue;
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}
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// Change the filepath.
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filepath = buffer;
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// Run the stat again, with the real file.
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if (stat(filepath, &statbuf) == -1) {
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printf("cat: %s: %s\n", filepath, strerror(errno));
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continue;
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}
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}
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// Check if it is a directory.
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if (S_ISDIR(statbuf.st_mode)) {
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printf("cat: %s: Is a directory\n", filepath);
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continue;
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}
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// If it is a regular file, open the file in read-only.
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if (S_ISREG(statbuf.st_mode)) {
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fd = open(filepath, O_RDONLY, 0);
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}
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if (fd < 0) {
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printf("cat: %s: %s\n", filepath, strerror(errno));
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continue;
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}
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ssize_t bytes_read = 0;
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// Put on the standard output the characters.
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while ((bytes_read = read(fd, buffer, BUFSIZ)) > 0) {
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write(STDOUT_FILENO, buffer, bytes_read);
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}
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close(fd);
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}
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putchar('\n');
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return 0;
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}
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