/*
 * 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/stat.h>
#include <sys/types.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円';

 /* 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円';
 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円';

 /*
 * 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円';

 /* 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;
}