/*
   *	docproc is a simple preprocessor for the template files
   *      used as placeholders for the kernel internal documentation.
   *	docproc is used for documentation-frontend and
   *      dependency-generator.
   *	The two usages have in common that they require
   *	some knowledge of the .tmpl syntax, therefore they
   *	are kept together.
   *
   *	documentation-frontend
   *		Scans the template file and call kernel-doc for
   *		all occurrences of ![EIF]file

   *		Beforehand each referenced file is scanned for
   *		any symbols that are exported via these macros:
   *			EXPORT_SYMBOL(), EXPORT_SYMBOL_GPL(), &
   *			EXPORT_SYMBOL_GPL_FUTURE()

   *		This is used to create proper -function and
   *		-nofunction arguments in calls to kernel-doc.
   *		Usage: docproc doc file.tmpl
   *
   *	dependency-generator:
   *		Scans the template file and list all files
   *		referenced in a format recognized by make.
   *		Usage:	docproc depend file.tmpl
   *		Writes dependency information to stdout
   *		in the following format:
   *		file.tmpl src.c	src2.c
   *		The filenames are obtained from the following constructs:
   *		!Efilename
   *		!Ifilename
   *		!Dfilename
   *		!Ffilename

   *		!Pfilename

   *
   */

  #define _GNU_SOURCE

  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <ctype.h>
  #include <unistd.h>
  #include <limits.h>

  #include <errno.h>

  #include <sys/types.h>
  #include <sys/wait.h>
  
  /* exitstatus is used to keep track of any failing calls to kernel-doc,
   * but execution continues. */
  int exitstatus = 0;
  
  typedef void DFL(char *);
  DFL *defaultline;
  
  typedef void FILEONLY(char * file);
  FILEONLY *internalfunctions;
  FILEONLY *externalfunctions;
  FILEONLY *symbolsonly;

  FILEONLY *findall;

  typedef void FILELINE(char * file, char * line);

  FILELINE * singlefunctions;
  FILELINE * entity_system;

  FILELINE * docsection;

  
  #define MAXLINESZ     2048
  #define MAXFILES      250
  #define KERNELDOCPATH "scripts/"
  #define KERNELDOC     "kernel-doc"
  #define DOCBOOK       "-docbook"

  #define LIST          "-list"

  #define FUNCTION      "-function"
  #define NOFUNCTION    "-nofunction"

  #define NODOCSECTIONS "-no-doc-sections"

  static char *srctree, *kernsrctree;

  static char **all_list = NULL;
  static int all_list_len = 0;
  
  static void consume_symbol(const char *sym)
  {
  	int i;
  
  	for (i = 0; i < all_list_len; i++) {
  		if (!all_list[i])
  			continue;
  		if (strcmp(sym, all_list[i]))
  			continue;
  		all_list[i] = NULL;
  		break;
  	}
  }

  static void usage (void)

  {
  	fprintf(stderr, "Usage: docproc {doc|depend} file
  ");
  	fprintf(stderr, "Input is read from file.tmpl. Output is sent to stdout
  ");
  	fprintf(stderr, "doc: frontend when generating kernel documentation
  ");
  	fprintf(stderr, "depend: generate list of files referenced within file
  ");

  	fprintf(stderr, "Environment variable SRCTREE: absolute path to sources.
  ");
  	fprintf(stderr, "                     KBUILD_SRC: absolute path to kernel source tree.
  ");

  }
  
  /*

   * Execute kernel-doc with parameters given in svec

   */

  static void exec_kernel_doc(char **svec)

  {
  	pid_t pid;
  	int ret;
  	char real_filename[PATH_MAX + 1];
  	/* Make sure output generated so far are flushed */
  	fflush(stdout);

  	switch (pid=fork()) {

  		case -1:
  			perror("fork");
  			exit(1);
  		case  0:
  			memset(real_filename, 0, sizeof(real_filename));

  			strncat(real_filename, kernsrctree, PATH_MAX);
  			strncat(real_filename, "/" KERNELDOCPATH KERNELDOC,

  					PATH_MAX - strlen(real_filename));
  			execvp(real_filename, svec);
  			fprintf(stderr, "exec ");
  			perror(real_filename);
  			exit(1);
  		default:
  			waitpid(pid, &ret ,0);
  	}
  	if (WIFEXITED(ret))
  		exitstatus |= WEXITSTATUS(ret);
  	else
  		exitstatus = 0xff;
  }
  
  /* Types used to create list of all exported symbols in a number of files */
  struct symbols
  {
  	char *name;
  };
  
  struct symfile
  {
  	char *filename;
  	struct symbols *symbollist;
  	int symbolcnt;
  };
  
  struct symfile symfilelist[MAXFILES];
  int symfilecnt = 0;

  static void add_new_symbol(struct symfile *sym, char * symname)

  {
  	sym->symbollist =
            realloc(sym->symbollist, (sym->symbolcnt + 1) * sizeof(char *));
  	sym->symbollist[sym->symbolcnt++].name = strdup(symname);
  }
  
  /* Add a filename to the list */

  static struct symfile * add_new_file(char * filename)

  {
  	symfilelist[symfilecnt++].filename = strdup(filename);
  	return &symfilelist[symfilecnt - 1];
  }

  /* Check if file already are present in the list */

  static struct symfile * filename_exist(char * filename)

  {
  	int i;
  	for (i=0; i < symfilecnt; i++)
  		if (strcmp(symfilelist[i].filename, filename) == 0)
  			return &symfilelist[i];
  	return NULL;
  }
  
  /*
   * List all files referenced within the template file.
   * Files are separated by tabs.
   */

  static void adddep(char * file)		   { printf("\t%s", file); }
  static void adddep2(char * file, char * line)     { line = line; adddep(file); }
  static void noaction(char * line)		   { line = line; }
  static void noaction2(char * file, char * line)   { file = file; line = line; }

  
  /* Echo the line without further action */

  static void printline(char * line)               { printf("%s", line); }

  
  /*

   * Find all symbols in filename that are exported with EXPORT_SYMBOL &
   * EXPORT_SYMBOL_GPL (& EXPORT_SYMBOL_GPL_FUTURE implicitly).

   * All symbols located are stored in symfilelist.
   */

  static void find_export_symbols(char * filename)

  {
  	FILE * fp;
  	struct symfile *sym;
  	char line[MAXLINESZ];
  	if (filename_exist(filename) == NULL) {
  		char real_filename[PATH_MAX + 1];
  		memset(real_filename, 0, sizeof(real_filename));

  		strncat(real_filename, srctree, PATH_MAX);

  		strncat(real_filename, "/", PATH_MAX - strlen(real_filename));

  		strncat(real_filename, filename,
  				PATH_MAX - strlen(real_filename));
  		sym = add_new_file(filename);
  		fp = fopen(real_filename, "r");

  		if (fp == NULL)	{

  			fprintf(stderr, "docproc: ");
  			perror(real_filename);

  			exit(1);

  		}

  		while (fgets(line, MAXLINESZ, fp)) {

  			char *p;
  			char *e;

  			if (((p = strstr(line, "EXPORT_SYMBOL_GPL")) != NULL) ||
                              ((p = strstr(line, "EXPORT_SYMBOL")) != NULL)) {

  				/* Skip EXPORT_SYMBOL{_GPL} */
  				while (isalnum(*p) || *p == '_')
  					p++;

  				/* Remove parentheses & additional whitespace */

  				while (isspace(*p))
  					p++;
  				if (*p != '(')
  					continue; /* Syntax error? */
  				else
  					p++;
  				while (isspace(*p))
  					p++;
  				e = p;
  				while (isalnum(*e) || *e == '_')
  					e++;
  				*e = '\0';
  				add_new_symbol(sym, p);
  			}
  		}
  		fclose(fp);
  	}
  }
  
  /*
   * Document all external or internal functions in a file.
   * Call kernel-doc with following parameters:
   * kernel-doc -docbook -nofunction function_name1 filename

   * Function names are obtained from all the src files

   * by find_export_symbols.
   * intfunc uses -nofunction
   * extfunc uses -function
   */

  static void docfunctions(char * filename, char * type)

  {
  	int i,j;
  	int symcnt = 0;
  	int idx = 0;
  	char **vec;
  
  	for (i=0; i <= symfilecnt; i++)
  		symcnt += symfilelist[i].symbolcnt;

  	vec = malloc((2 + 2 * symcnt + 3) * sizeof(char *));

  	if (vec == NULL) {
  		perror("docproc: ");
  		exit(1);
  	}
  	vec[idx++] = KERNELDOC;
  	vec[idx++] = DOCBOOK;

  	vec[idx++] = NODOCSECTIONS;

  	for (i=0; i < symfilecnt; i++) {
  		struct symfile * sym = &symfilelist[i];
  		for (j=0; j < sym->symbolcnt; j++) {
  			vec[idx++]     = type;

  			consume_symbol(sym->symbollist[j].name);

  			vec[idx++] = sym->symbollist[j].name;
  		}
  	}
  	vec[idx++]     = filename;
  	vec[idx] = NULL;
  	printf("<!-- %s -->
  ", filename);
  	exec_kernel_doc(vec);
  	fflush(stdout);
  	free(vec);
  }

  static void intfunc(char * filename) {	docfunctions(filename, NOFUNCTION); }
  static void extfunc(char * filename) { docfunctions(filename, FUNCTION);   }

  
  /*

   * Document specific function(s) in a file.

   * Call kernel-doc with the following parameters:
   * kernel-doc -docbook -function function1 [-function function2]
   */

  static void singfunc(char * filename, char * line)

  {
  	char *vec[200]; /* Enough for specific functions */
          int i, idx = 0;
          int startofsym = 1;
  	vec[idx++] = KERNELDOC;
  	vec[idx++] = DOCBOOK;

          /* Split line up in individual parameters preceded by FUNCTION */

          for (i=0; line[i]; i++) {
                  if (isspace(line[i])) {
                          line[i] = '\0';
                          startofsym = 1;
                          continue;
                  }
                  if (startofsym) {
                          startofsym = 0;
                          vec[idx++] = FUNCTION;
                          vec[idx++] = &line[i];
                  }
          }

  	for (i = 0; i < idx; i++) {
          	if (strcmp(vec[i], FUNCTION))
          		continue;
  		consume_symbol(vec[i + 1]);
  	}

  	vec[idx++] = filename;
  	vec[idx] = NULL;
  	exec_kernel_doc(vec);
  }
  
  /*

   * Insert specific documentation section from a file.
   * Call kernel-doc with the following parameters:
   * kernel-doc -docbook -function "doc section" filename
   */

  static void docsect(char *filename, char *line)

  {
  	char *vec[6]; /* kerneldoc -docbook -function "section" file NULL */
  	char *s;
  
  	for (s = line; *s; s++)
  		if (*s == '
  ')
  			*s = '\0';

  	if (asprintf(&s, "DOC: %s", line) < 0) {
  		perror("asprintf");
  		exit(1);
  	}

  	consume_symbol(s);
  	free(s);

  	vec[0] = KERNELDOC;
  	vec[1] = DOCBOOK;
  	vec[2] = FUNCTION;
  	vec[3] = line;
  	vec[4] = filename;
  	vec[5] = NULL;
  	exec_kernel_doc(vec);
  }

  static void find_all_symbols(char *filename)
  {
  	char *vec[4]; /* kerneldoc -list file NULL */
  	pid_t pid;
  	int ret, i, count, start;
  	char real_filename[PATH_MAX + 1];
  	int pipefd[2];
  	char *data, *str;
  	size_t data_len = 0;
  
  	vec[0] = KERNELDOC;
  	vec[1] = LIST;
  	vec[2] = filename;
  	vec[3] = NULL;
  
  	if (pipe(pipefd)) {
  		perror("pipe");
  		exit(1);
  	}
  
  	switch (pid=fork()) {
  		case -1:
  			perror("fork");
  			exit(1);
  		case  0:
  			close(pipefd[0]);
  			dup2(pipefd[1], 1);
  			memset(real_filename, 0, sizeof(real_filename));
  			strncat(real_filename, kernsrctree, PATH_MAX);
  			strncat(real_filename, "/" KERNELDOCPATH KERNELDOC,
  					PATH_MAX - strlen(real_filename));
  			execvp(real_filename, vec);
  			fprintf(stderr, "exec ");
  			perror(real_filename);
  			exit(1);
  		default:
  			close(pipefd[1]);
  			data = malloc(4096);
  			do {
  				while ((ret = read(pipefd[0],
  						   data + data_len,
  						   4096)) > 0) {
  					data_len += ret;
  					data = realloc(data, data_len + 4096);
  				}
  			} while (ret == -EAGAIN);
  			if (ret != 0) {
  				perror("read");
  				exit(1);
  			}
  			waitpid(pid, &ret ,0);
  	}
  	if (WIFEXITED(ret))
  		exitstatus |= WEXITSTATUS(ret);
  	else
  		exitstatus = 0xff;
  
  	count = 0;
  	/* poor man's strtok, but with counting */
  	for (i = 0; i < data_len; i++) {
  		if (data[i] == '
  ') {
  			count++;
  			data[i] = '\0';
  		}
  	}
  	start = all_list_len;
  	all_list_len += count;
  	all_list = realloc(all_list, sizeof(char *) * all_list_len);
  	str = data;
  	for (i = 0; i < data_len && start != all_list_len; i++) {
  		if (data[i] == '\0') {
  			all_list[start] = str;
  			str = data + i + 1;
  			start++;
  		}
  	}
  }

  /*

   * Parse file, calling action specific functions for:
   * 1) Lines containing !E
   * 2) Lines containing !I
   * 3) Lines containing !D
   * 4) Lines containing !F

   * 5) Lines containing !P

   * 6) Lines containing !C
   * 7) Default lines - lines not matching the above

   */

  static void parse_file(FILE *infile)

  {
  	char line[MAXLINESZ];

  	char * s;

  	while (fgets(line, MAXLINESZ, infile)) {

  		if (line[0] == '!') {
  			s = line + 2;
  			switch (line[1]) {
  				case 'E':
  					while (*s && !isspace(*s)) s++;
  					*s = '\0';
  					externalfunctions(line+2);
  					break;
  				case 'I':
  					while (*s && !isspace(*s)) s++;
  					*s = '\0';
  					internalfunctions(line+2);
  					break;
  				case 'D':
  					while (*s && !isspace(*s)) s++;
                                          *s = '\0';
                                          symbolsonly(line+2);
                                          break;
  				case 'F':
  					/* filename */
  					while (*s && !isspace(*s)) s++;
  					*s++ = '\0';
                                          /* function names */
  					while (isspace(*s))
  						s++;
  					singlefunctions(line +2, s);
  					break;

  				case 'P':
  					/* filename */
  					while (*s && !isspace(*s)) s++;
  					*s++ = '\0';
  					/* DOC: section name */
  					while (isspace(*s))
  						s++;
  					docsection(line + 2, s);
  					break;

  				case 'C':
  					while (*s && !isspace(*s)) s++;
  					*s = '\0';
  					if (findall)
  						findall(line+2);
  					break;

  				default:
  					defaultline(line);
  			}

  		} else {

  			defaultline(line);
  		}
  	}
  	fflush(stdout);
  }
  
  
  int main(int argc, char *argv[])
  {
  	FILE * infile;

  	int i;

  
  	srctree = getenv("SRCTREE");
  	if (!srctree)
  		srctree = getcwd(NULL, 0);

  	kernsrctree = getenv("KBUILD_SRC");

  	if (!kernsrctree || !*kernsrctree)

  		kernsrctree = srctree;

  	if (argc != 3) {
  		usage();
  		exit(1);
  	}
  	/* Open file, exit on error */
  	infile = fopen(argv[2], "r");
          if (infile == NULL) {
                  fprintf(stderr, "docproc: ");
                  perror(argv[2]);
                  exit(2);
          }

  	if (strcmp("doc", argv[1]) == 0) {

  		/* Need to do this in two passes.
  		 * First pass is used to collect all symbols exported

  		 * in the various files;

  		 * Second pass generate the documentation.

  		 * This is required because some functions are declared

  		 * and exported in different files :-((
  		 */
  		/* Collect symbols */
  		defaultline       = noaction;
  		internalfunctions = find_export_symbols;
  		externalfunctions = find_export_symbols;
  		symbolsonly       = find_export_symbols;
  		singlefunctions   = noaction2;

  		docsection        = noaction2;

  		findall           = find_all_symbols;

  		parse_file(infile);
  
  		/* Rewind to start from beginning of file again */
  		fseek(infile, 0, SEEK_SET);
  		defaultline       = printline;
  		internalfunctions = intfunc;
  		externalfunctions = extfunc;
  		symbolsonly       = printline;
  		singlefunctions   = singfunc;

  		docsection        = docsect;

  		findall           = NULL;

  
  		parse_file(infile);

  
  		for (i = 0; i < all_list_len; i++) {
  			if (!all_list[i])
  				continue;
  			fprintf(stderr, "Warning: didn't use docs for %s
  ",
  				all_list[i]);
  		}

  	} else if (strcmp("depend", argv[1]) == 0) {

  		/* Create first part of dependency chain
  		 * file.tmpl */
  		printf("%s\t", argv[2]);
  		defaultline       = noaction;
  		internalfunctions = adddep;
  		externalfunctions = adddep;
  		symbolsonly       = adddep;
  		singlefunctions   = adddep2;

  		docsection        = adddep2;

  		findall           = adddep;

  		parse_file(infile);
  		printf("
  ");

  	} else {

  		fprintf(stderr, "Unknown option: %s
  ", argv[1]);
  		exit(1);
  	}
  	fclose(infile);
  	fflush(stdout);
  	return exitstatus;
  }