Usage of /usr/bin/file to get the MIME type of a file

file-mimetype.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

bool getMimeType(const char* filePath, char* output, int maxOutputLength) {
    const char* COMMAND_BASE = "/usr/bin/file -b --mime-type ";

    // + 1 for null terminator
    char* command = calloc(1, strlen(COMMAND_BASE) + strlen(filePath) + 1);

    strcpy(command, COMMAND_BASE);
    strcat(command, filePath);
    FILE* p = popen(command, "r");
    free(command);
    if (p == NULL)
        return false;
    fgets(output, maxOutputLength, p);
    return 0 == pclose(p);
}

int main(int argc, char* argv[]) {
    if (argc < 2) {
        printf("Expected one argument: path to file\n");
        return 1;
    }

    const int MAX_OUTPUT_LENGTH = 256;
    char mimeType[MAX_OUTPUT_LENGTH];
    if (getMimeType(argv[1], mimeType, MAX_OUTPUT_LENGTH)) {
        printf("MIME type: %s\n", mimeType);
        return 0;
    } else {
        printf("Failed to get MIME type.\n");
        return 1;
    }
}