/*
 *      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 <getopt.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.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 RST           "-rst"
#define LIST          "-list"
#define FUNCTION      "-function"
#define NOFUNCTION    "-nofunction"
#define NODOCSECTIONS "-no-doc-sections"
#define SHOWNOTFOUND  "-show-not-found"

enum file_format {
        FORMAT_AUTO,
        FORMAT_DOCBOOK,
        FORMAT_RST,
};

static enum file_format file_format = FORMAT_AUTO;

#define KERNELDOC_FORMAT        (file_format == FORMAT_RST ? RST : DOCBOOK)

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 [{--docbook|--rst}] {doc|depend} file\n");
        fprintf(stderr, "Input is read from file.tmpl. Output is sent to stdout\n");
        fprintf(stderr, "doc: frontend when generating kernel documentation\n");
        fprintf(stderr, "depend: generate list of files referenced within file\n");
        fprintf(stderr, "Environment variable SRCTREE: absolute path to sources.\n");
        fprintf(stderr, "                     KBUILD_SRC: absolute path to kernel source tree.\n");
}

/*
 * 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|-rst] -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++] = KERNELDOC_FORMAT;
        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;
        if (file_format == FORMAT_RST)
                printf(".. %s\n", filename);
        else
                printf("<!-- %s -->\n", 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++] = KERNELDOC_FORMAT;
        vec[idx++] = SHOWNOTFOUND;

        /* 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)
{
        /* kerneldoc -docbook -show-not-found -function "section" file NULL */
        char *vec[7];
        char *s;

        for (s = line; *s; s++)
                if (*s == '\n')
                        *s = '\0';

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

        vec[0] = KERNELDOC;
        vec[1] = KERNELDOC_FORMAT;
        vec[2] = SHOWNOTFOUND;
        vec[3] = FUNCTION;
        vec[4] = line;
        vec[5] = filename;
        vec[6] = 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] == '\n') {
                        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++;
                }
        }
}

/*
 * Terminate s at first space, if any. If there was a space, return pointer to
 * the character after that. Otherwise, return pointer to the terminating NUL.
 */
static char *chomp(char *s)
{
        while (*s && !isspace(*s))
                s++;

        if (*s)
                *s++ = '\0';

        return s;
}

/* Return pointer to directive content, or NULL if not a directive. */
static char *is_directive(char *line)
{
        if (file_format == FORMAT_DOCBOOK && line[0] == '!')
                return line + 1;
        else if (file_format == FORMAT_RST && !strncmp(line, ".. !", 4))
                return line + 4;

        return NULL;
}

/*
 * 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 *p, *s;
        while (fgets(line, MAXLINESZ, infile)) {
                p = is_directive(line);
                if (!p) {
                        defaultline(line);
                        continue;
                }

                switch (*p++) {
                case 'E':
                        chomp(p);
                        externalfunctions(p);
                        break;
                case 'I':
                        chomp(p);
                        internalfunctions(p);
                        break;
                case 'D':
                        chomp(p);
                        symbolsonly(p);
                        break;
                case 'F':
                        /* filename */
                        s = chomp(p);
                        /* function names */
                        while (isspace(*s))
                                s++;
                        singlefunctions(p, s);
                        break;
                case 'P':
                        /* filename */
                        s = chomp(p);
                        /* DOC: section name */
                        while (isspace(*s))
                                s++;
                        docsection(p, s);
                        break;
                case 'C':
                        chomp(p);
                        if (findall)
                                findall(p);
                        break;
                default:
                        defaultline(line);
                }
        }
        fflush(stdout);
}

/*
 * Is this a RestructuredText template?  Answer the question by seeing if its
 * name ends in ".rst".
 */
static int is_rst(const char *file)
{
        char *dot = strrchr(file, '.');

        return dot && !strcmp(dot + 1, "rst");
}

enum opts {
        OPT_DOCBOOK,
        OPT_RST,
        OPT_HELP,
};

int main(int argc, char *argv[])
{
        const char *subcommand, *filename;
        FILE * infile;
        int i;

        srctree = getenv("SRCTREE");
        if (!srctree)
                srctree = getcwd(NULL, 0);
        kernsrctree = getenv("KBUILD_SRC");
        if (!kernsrctree || !*kernsrctree)
                kernsrctree = srctree;

        for (;;) {
                int c;
                struct option opts[] = {
                        { "docbook",    no_argument, NULL, OPT_DOCBOOK },
                        { "rst",        no_argument, NULL, OPT_RST },
                        { "help",       no_argument, NULL, OPT_HELP },
                        {}
                };

                c = getopt_long_only(argc, argv, "", opts, NULL);
                if (c == -1)
                        break;

                switch (c) {
                case OPT_DOCBOOK:
                        file_format = FORMAT_DOCBOOK;
                        break;
                case OPT_RST:
                        file_format = FORMAT_RST;
                        break;
                case OPT_HELP:
                        usage();
                        return 0;
                default:
                case '?':
                        usage();
                        return 1;
                }
        }

        argc -= optind;
        argv += optind;

        if (argc != 2) {
                usage();
                exit(1);
        }

        subcommand = argv[0];
        filename = argv[1];

        if (file_format == FORMAT_AUTO)
                file_format = is_rst(filename) ? FORMAT_RST : FORMAT_DOCBOOK;

        /* Open file, exit on error */
        infile = fopen(filename, "r");
        if (infile == NULL) {
                fprintf(stderr, "docproc: ");
                perror(filename);
                exit(2);
        }

        if (strcmp("doc", subcommand) == 0) {
                if (file_format == FORMAT_RST) {
                        time_t t = time(NULL);
                        printf(".. generated from %s by docproc %s\n",
                               filename, ctime(&t));
                }

                /* 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\n",
                                all_list[i]);
                }
        } else if (strcmp("depend", subcommand) == 0) {
                /* Create first part of dependency chain
                 * file.tmpl */
                printf("%s\t", filename);
                defaultline       = noaction;
                internalfunctions = adddep;
                externalfunctions = adddep;
                symbolsonly       = adddep;
                singlefunctions   = adddep2;
                docsection        = adddep2;
                findall           = adddep;
                parse_file(infile);
                printf("\n");
        } else {
                fprintf(stderr, "Unknown option: %s\n", subcommand);
                exit(1);
        }
        fclose(infile);
        fflush(stdout);
        return exitstatus;
}