/*
 * (C) Copyright 2011 Free Electrons
 * David Wagner <david.wagner@free-electrons.com>
 *
 * Inspired from envcrc.c:
 * (C) Copyright 2001
 * Paolo Scaffardi, AIRVENT SAM s.p.a - RIMINI(ITALY), arsenio@tin.it
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <libgen.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>

#include "compiler.h"
#include <u-boot/crc.h>
#include <version.h>

#define CRC_SIZE sizeof(uint32_t)

static void usage(const char *exec_name)
{
        fprintf(stderr, "%s [-h] [-r] [-b] [-p <byte>] -s <environment partition size> -o <output> <input file>\n"
               "\n"
               "This tool takes a key=value input file (same as would a `printenv' show) and generates the corresponding environment image, ready to be flashed.\n"
               "\n"
               "\tThe input file is in format:\n"
               "\t\tkey1=value1\n"
               "\t\tkey2=value2\n"
               "\t\t...\n"
               "\tEmpty lines are skipped, and lines with a # in the first\n"
               "\tcolumn are treated as comments (also skipped).\n"
               "\t-r : the environment has multiple copies in flash\n"
               "\t-b : the target is big endian (default is little endian)\n"
               "\t-p <byte> : fill the image with <byte> bytes instead of 0xff bytes\n"
               "\t-V : print version information and exit\n"
               "\n"
               "If the input file is \"-\", data is read from standard input\n",
               exec_name);
}

long int xstrtol(const char *s)
{
        long int tmp;

        errno = 0;
        tmp = strtol(s, NULL, 0);
        if (!errno)
                return tmp;

        if (errno == ERANGE)
                fprintf(stderr, "Bad integer format: %s\n",  s);
        else
                fprintf(stderr, "Error while parsing %s: %s\n", s,
                                strerror(errno));

        exit(EXIT_FAILURE);
}

int main(int argc, char **argv)
{
        uint32_t crc, targetendian_crc;
        const char *txt_filename = NULL, *bin_filename = NULL;
        int txt_fd, bin_fd;
        unsigned char *dataptr, *envptr;
        unsigned char *filebuf = NULL;
        unsigned int filesize = 0, envsize = 0, datasize = 0;
        int bigendian = 0;
        int redundant = 0;
        unsigned char padbyte = 0xff;

        int option;
        int ret = EXIT_SUCCESS;

        struct stat txt_file_stat;

        int fp, ep;
        const char *prg;

        prg = basename(argv[0]);

        /* Turn off getopt()'s internal error message */
        opterr = 0;

        /* Parse the cmdline */
        while ((option = getopt(argc, argv, ":s:o:rbp:hV")) != -1) {
                switch (option) {
                case 's':
                        datasize = xstrtol(optarg);
                        break;
                case 'o':
                        bin_filename = strdup(optarg);
                        if (!bin_filename) {
                                fprintf(stderr, "Can't strdup() the output filename\n");
                                return EXIT_FAILURE;
                        }
                        break;
                case 'r':
                        redundant = 1;
                        break;
                case 'b':
                        bigendian = 1;
                        break;
                case 'p':
                        padbyte = xstrtol(optarg);
                        break;
                case 'h':
                        usage(prg);
                        return EXIT_SUCCESS;
                case 'V':
                        printf("%s version %s\n", prg, PLAIN_VERSION);
                        return EXIT_SUCCESS;
                case ':':
                        fprintf(stderr, "Missing argument for option -%c\n",
                                optopt);
                        usage(prg);
                        return EXIT_FAILURE;
                default:
                        fprintf(stderr, "Wrong option -%c\n", optopt);
                        usage(prg);
                        return EXIT_FAILURE;
                }
        }

        /* Check datasize and allocate the data */
        if (datasize == 0) {
                fprintf(stderr, "Please specify the size of the environment partition.\n");
                usage(prg);
                return EXIT_FAILURE;
        }

        dataptr = malloc(datasize * sizeof(*dataptr));
        if (!dataptr) {
                fprintf(stderr, "Can't alloc %d bytes for dataptr.\n",
                                datasize);
                return EXIT_FAILURE;
        }

        /*
         * envptr points to the beginning of the actual environment (after the
         * crc and possible `redundant' byte
         */
        envsize = datasize - (CRC_SIZE + redundant);
        envptr = dataptr + CRC_SIZE + redundant;

        /* Pad the environment with the padding byte */
        memset(envptr, padbyte, envsize);

        /* Open the input file ... */
        if (optind >= argc || strcmp(argv[optind], "-") == 0) {
                int readbytes = 0;
                int readlen = sizeof(*envptr) * 4096;
                txt_fd = STDIN_FILENO;

                do {
                        filebuf = realloc(filebuf, readlen);
                        if (!filebuf) {
                                fprintf(stderr, "Can't realloc memory for the input file buffer\n");
                                return EXIT_FAILURE;
                        }
                        readbytes = read(txt_fd, filebuf + filesize, readlen);
                        if (errno) {
                                fprintf(stderr, "Error while reading stdin: %s\n",
                                                strerror(errno));
                                return EXIT_FAILURE;
                        }
                        filesize += readbytes;
                } while (readbytes == readlen);

        } else {
                txt_filename = argv[optind];
                txt_fd = open(txt_filename, O_RDONLY);
                if (txt_fd == -1) {
                        fprintf(stderr, "Can't open \"%s\": %s\n",
                                        txt_filename, strerror(errno));
                        return EXIT_FAILURE;
                }
                /* ... and check it */
                ret = fstat(txt_fd, &txt_file_stat);
                if (ret == -1) {
                        fprintf(stderr, "Can't stat() on \"%s\": %s\n",
                                        txt_filename, strerror(errno));
                        return EXIT_FAILURE;
                }

                filesize = txt_file_stat.st_size;

                filebuf = mmap(NULL, sizeof(*envptr) * filesize, PROT_READ,
                               MAP_PRIVATE, txt_fd, 0);
                if (filebuf == MAP_FAILED) {
                        fprintf(stderr, "mmap (%zu bytes) failed: %s\n",
                                        sizeof(*envptr) * filesize,
                                        strerror(errno));
                        fprintf(stderr, "Falling back to read()\n");

                        filebuf = malloc(sizeof(*envptr) * filesize);
                        ret = read(txt_fd, filebuf, sizeof(*envptr) * filesize);
                        if (ret != sizeof(*envptr) * filesize) {
                                fprintf(stderr, "Can't read the whole input file (%zu bytes): %s\n",
                                        sizeof(*envptr) * filesize,
                                        strerror(errno));

                                return EXIT_FAILURE;
                        }
                }
                ret = close(txt_fd);
        }

        /* Parse a byte at time until reaching the file OR until the environment fills
         * up. Check ep against envsize - 1 to allow for extra trailing '\0'. */
        for (fp = 0, ep = 0 ; fp < filesize && ep < envsize - 1; fp++) {
                if (filebuf[fp] == '\n') {
                        if (fp == 0 || filebuf[fp-1] == '\n') {
                                /*
                                 * Skip empty lines.
                                 */
                                continue;
                        } else if (filebuf[fp-1] == '\\') {
                                /*
                                 * Embedded newline in a variable.
                                 *
                                 * The backslash was added to the envptr; rewind
                                 * and replace it with a newline
                                 */
                                ep--;
                                envptr[ep++] = '\n';
                        } else {
                                /* End of a variable */
                                envptr[ep++] = '\0';
                        }
                } else if ((fp == 0 || filebuf[fp-1] == '\n') && filebuf[fp] == '#') {
                        /* Comment, skip the line. */
                        while (++fp < filesize && filebuf[fp] != '\n')
                        continue;
                } else {
                        envptr[ep++] = filebuf[fp];
                }
        }
        /* If there are more bytes in the file still, it means the env filled up
         * before parsing the whole file.  Eat comments & whitespace here to see if
         * there was anything meaning full left in the file, and if so, throw a error
         * and exit. */
        for( ; fp < filesize; fp++ )
        {
                if (filebuf[fp] == '\n') {
                        if (fp == 0 || filebuf[fp-1] == '\n') {
                                /* Ignore blank lines */
                                continue;
                        }
                } else if ((fp == 0 || filebuf[fp-1] == '\n') && filebuf[fp] == '#') {
                        while (++fp < filesize && filebuf[fp] != '\n')
                        continue;
                } else {
                        fprintf(stderr, "The environment file is too large for the target environment storage\n");
                        return EXIT_FAILURE;
                }
        }
        /*
         * Make sure there is a final '\0'
         * And do it again on the next byte to mark the end of the environment.
         */
        if (envptr[ep-1] != '\0') {
                envptr[ep++] = '\0';
                /*
                 * The text file doesn't have an ending newline.  We need to
                 * check the env size again to make sure we have room for two \0
                 */
                if (ep >= envsize) {
                        fprintf(stderr, "The environment file is too large for the target environment storage\n");
                        return EXIT_FAILURE;
                }
                envptr[ep] = '\0';
        } else {
                envptr[ep] = '\0';
        }

        /* Computes the CRC and put it at the beginning of the data */
        crc = crc32(0, envptr, envsize);
        targetendian_crc = bigendian ? cpu_to_be32(crc) : cpu_to_le32(crc);

        memcpy(dataptr, &targetendian_crc, sizeof(targetendian_crc));
        if (redundant)
                dataptr[sizeof(targetendian_crc)] = 1;

        if (!bin_filename || strcmp(bin_filename, "-") == 0) {
                bin_fd = STDOUT_FILENO;
        } else {
                bin_fd = creat(bin_filename, S_IRUSR | S_IWUSR | S_IRGRP |
                                             S_IWGRP);
                if (bin_fd == -1) {
                        fprintf(stderr, "Can't open output file \"%s\": %s\n",
                                        bin_filename, strerror(errno));
                        return EXIT_FAILURE;
                }
        }

        if (write(bin_fd, dataptr, sizeof(*dataptr) * datasize) !=
                        sizeof(*dataptr) * datasize) {
                fprintf(stderr, "write() failed: %s\n", strerror(errno));
                return EXIT_FAILURE;
        }

        ret = close(bin_fd);

        return ret;
}