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/*

 * split-include.c

 *

 * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>.

 * This is a C version of syncdep.pl by Werner Almesberger.

 *

 * This program takes autoconf.h as input and outputs a directory full

 * of one-line include files, merging onto the old values.

 *

 * Think of the configuration options as key-value pairs.  Then there

 * are five cases:

 *

 *    key      old value   new value   action

 *

 *    KEY-1    VALUE-1     VALUE-1     leave file alone

 *    KEY-2    VALUE-2A    VALUE-2B    write VALUE-2B into file

 *    KEY-3    -           VALUE-3     write VALUE-3  into file

 *    KEY-4    VALUE-4     -           write an empty file

 *    KEY-5    (empty)     -           leave old empty file alone

 */

#include <sys/types.h>

#include <sys/stat.h>

#include <ctype.h>

#include <errno.h>

#include <fcntl.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#define ERROR_EXIT(strExit)                                             \

    {                                                                   \

        const int errnoSave = errno;                                    \

        fprintf(stderr, "%s: ", str_my_name);                           \

        errno = errnoSave;                                              \

        perror((strExit));                                              \

        exit(1);                                                        \

    }

int main(int argc, const char * argv [])

{

    const char * str_my_name;

    const char * str_file_autoconf;

    const char * str_dir_config;

    FILE * fp_config;

    FILE * fp_target;

    FILE * fp_find;

    int buffer_size;

    char * line;

    char * old_line;

    char * list_target;

    char * ptarget;

    struct stat stat_buf;

    /* Check arg count. */

    if (argc != 3)

    {

        fprintf(stderr, "%s: wrong number of arguments.\n", argv[0]);

        exit(1);

    }

    str_my_name       = argv[0];

    str_file_autoconf = argv[1];

    str_dir_config    = argv[2];

    /* Find a buffer size. */

    if (stat(str_file_autoconf, &stat_buf) != 0)

        ERROR_EXIT(str_file_autoconf);

    buffer_size = 2 * stat_buf.st_size + 4096;

    /* Allocate buffers. */

    if ( (line        = malloc(buffer_size)) == NULL

    ||   (old_line    = malloc(buffer_size)) == NULL

    ||   (list_target = malloc(buffer_size)) == NULL )

        ERROR_EXIT(str_file_autoconf);

    /* Open autoconfig file. */

    if ((fp_config = fopen(str_file_autoconf, "r")) == NULL)

        ERROR_EXIT(str_file_autoconf);

    /* Make output directory if needed. */

    if (stat(str_dir_config, &stat_buf) != 0)

    {

        if (mkdir(str_dir_config, 0755) != 0)

            ERROR_EXIT(str_dir_config);

    }

    /* Change to output directory. */

    if (chdir(str_dir_config) != 0)

        ERROR_EXIT(str_dir_config);

    /* Put initial separator into target list. */

    ptarget = list_target;

    *ptarget++ = '\n';

    /* Read config lines. */

    while (fgets(line, buffer_size, fp_config))

    {

        const char * str_config;

        int is_same;

        int itarget;

        if (line[0] != '#')

            continue;

        if ((str_config = strstr(line, "CONFIG_")) == NULL)

            continue;

        /* Make the output file name. */

        str_config += sizeof("CONFIG_") - 1;

        for (itarget = 0; !isspace((int)str_config[itarget]); itarget++)

        {

            char c = str_config[itarget];

            if (isupper((int)c)) c = tolower((int)c);

            if (c == '_')   c = '/';

            ptarget[itarget] = c;

        }

        ptarget[itarget++] = '.';

        ptarget[itarget++] = 'h';

        ptarget[itarget++] = '\0';

        /* Check for existing file. */

        is_same = 0;

        if ((fp_target = fopen(ptarget, "r")) != NULL)

        {

            fgets(old_line, buffer_size, fp_target);

            if (fclose(fp_target) != 0)

                ERROR_EXIT(ptarget);

            if (!strcmp(line, old_line))

                is_same = 1;

        }

        if (!is_same)

        {

            /* Auto-create directories. */

            int islash;

            for (islash = 0; islash < itarget; islash++)

            {

                if (ptarget[islash] == '/')

                {

                    ptarget[islash] = '\0';

                    if (stat(ptarget, &stat_buf) != 0

                    &&  mkdir(ptarget, 0755)     != 0)

                        ERROR_EXIT( ptarget );

                    ptarget[islash] = '/';

                }

            }

            /* Write the file. */

            if ((fp_target = fopen(ptarget, "w" )) == NULL)

                ERROR_EXIT(ptarget);

            fputs(line, fp_target);

            if (ferror(fp_target) || fclose(fp_target) != 0)

                ERROR_EXIT(ptarget);

        }

        /* Update target list */

        ptarget += itarget;

        *(ptarget-1) = '\n';

    }

    /*

     * Close autoconfig file.

     * Terminate the target list.

     */

    if (fclose(fp_config) != 0)

        ERROR_EXIT(str_file_autoconf);

    *ptarget = '\0';

    /*

     * Fix up existing files which have no new value.

     * This is Case 4 and Case 5.

     *

     * I re-read the tree and filter it against list_target.

     * This is crude.  But it avoids data copies.  Also, list_target

     * is compact and contiguous, so it easily fits into cache.

     *

     * Notice that list_target contains strings separated by \n,

     * with a \n before the first string and after the last.

     * fgets gives the incoming names a terminating \n.

     * So by having an initial \n, strstr will find exact matches.

     */

    fp_find = popen("find * -type f -name \"*.h\" -print", "r");

    if (fp_find == 0)

        ERROR_EXIT( "find" );

    line[0] = '\n';

    while (fgets(line+1, buffer_size, fp_find))

    {

        if (strstr(list_target, line) == NULL)

        {

            /*

             * This is an old file with no CONFIG_* flag in autoconf.h.

             */

            /* First strip the \n. */

            line[strlen(line)-1] = '\0';

            /* Grab size. */

            if (stat(line+1, &stat_buf) != 0)

                ERROR_EXIT(line);

            /* If file is not empty, make it empty and give it a fresh date. */

            if (stat_buf.st_size != 0)

            {

                if ((fp_target = fopen(line+1, "w")) == NULL)

                    ERROR_EXIT(line);

                if (fclose(fp_target) != 0)

                    ERROR_EXIT(line);

            }

        }

    }

    if (pclose(fp_find) != 0)

        ERROR_EXIT("find");

    return 0;

}