/**
 * @file cat.c
 * @brief Display file contents.
 *
 * Reads a file specified as the first argument (from shell)
 * and prints its contents to stdout. If no argument is given,
 * prints usage.
 *
 * Usage: cat <filepath>
 */

#include "syscalls.h"

int main(void) {
    /* Get the file path from the ARGS environment variable.
     * The shell sets ARGS to the arguments after the command name. */
    char path[128];
    if (getenv("ARG1", path, sizeof(path)) < 0) {
        puts("Usage: cat <file>\n");
        return 1;
    }

    /* Open the file */
    int32_t fd = open(path, 0);
    if (fd < 0) {
        puts("cat: ");
        puts(path);
        puts(": open failed\n");
        return 1;
    }

    /* Read and print in chunks */
    char buf[256];
    int32_t n;
    while ((n = read(fd, buf, sizeof(buf))) > 0) {
        write(1, buf, (uint32_t)n);
    }

    close(fd);
    return 0;
}