fuse_opt.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>

  Implementation of option parsing routines (dealing with `struct
  fuse_args`).

  This program can be distributed under the terms of the GNU LGPLv2.
  See the file COPYING.LIB
*/

#include "config.h"
#include "fuse_opt.h"
#include "fuse_misc.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

struct fuse_opt_context {
        void *data;
        const struct fuse_opt *opt;
        fuse_opt_proc_t proc;
        int argctr;
        int argc;
        char **argv;
        struct fuse_args outargs;
        char *opts;
        int nonopt;
};

void fuse_opt_free_args(struct fuse_args *args)
{
        if (args) {
                if (args->argv && args->allocated) {
                        int i;
                        for (i = 0; i < args->argc; i++)
                                free(args->argv[i]);
                        free(args->argv);
                }
                args->argc = 0;
                args->argv = NULL;
                args->allocated = 0;
        }
}

static int alloc_failed(void)
{
        fprintf(stderr, "fuse: memory allocation failed\n");
        return -1;
}

int fuse_opt_add_arg(struct fuse_args *args, const char *arg)
{
        char **newargv;
        char *newarg;

        assert(!args->argv || args->allocated);

        newarg = strdup(arg);
        if (!newarg)
                return alloc_failed();

        newargv = realloc(args->argv, (args->argc + 2) * sizeof(char *));
        if (!newargv) {
                free(newarg);
                return alloc_failed();
        }

        args->argv = newargv;
        args->allocated = 1;
        args->argv[args->argc++] = newarg;
        args->argv[args->argc] = NULL;
        return 0;
}

static int fuse_opt_insert_arg_common(struct fuse_args *args, int pos,
                                      const char *arg)
{
        assert(pos <= args->argc);
        if (fuse_opt_add_arg(args, arg) == -1)
                return -1;

        if (pos != args->argc - 1) {
                char *newarg = args->argv[args->argc - 1];
                memmove(&args->argv[pos + 1], &args->argv[pos],
                        sizeof(char *) * (args->argc - pos - 1));
                args->argv[pos] = newarg;
        }
        return 0;
}

int fuse_opt_insert_arg(struct fuse_args *args, int pos, const char *arg)
{
        return fuse_opt_insert_arg_common(args, pos, arg);
}

static int next_arg(struct fuse_opt_context *ctx, const char *opt)
{
        if (ctx->argctr + 1 >= ctx->argc) {
                fprintf(stderr, "fuse: missing argument after `%s'\n", opt);
                return -1;
        }
        ctx->argctr++;
        return 0;
}

static int add_arg(struct fuse_opt_context *ctx, const char *arg)
{
        return fuse_opt_add_arg(&ctx->outargs, arg);
}

static int add_opt_common(char **opts, const char *opt, int esc)
{
        unsigned oldlen = *opts ? strlen(*opts) : 0;
        char *d = realloc(*opts, oldlen + 1 + strlen(opt) * 2 + 1);

        if (!d)
                return alloc_failed();

        *opts = d;
        if (oldlen) {
                d += oldlen;
                *d++ = ',';
        }

        for (; *opt; opt++) {
                if (esc && (*opt == ',' || *opt == '\\'))
                        *d++ = '\\';
                *d++ = *opt;
        }
        *d = '\0';

        return 0;
}

int fuse_opt_add_opt(char **opts, const char *opt)
{
        return add_opt_common(opts, opt, 0);
}

int fuse_opt_add_opt_escaped(char **opts, const char *opt)
{
        return add_opt_common(opts, opt, 1);
}

static int add_opt(struct fuse_opt_context *ctx, const char *opt)
{
        return add_opt_common(&ctx->opts, opt, 1);
}

static int call_proc(struct fuse_opt_context *ctx, const char *arg, int key,
                     int iso)
{
        if (key == FUSE_OPT_KEY_DISCARD)
                return 0;

        if (key != FUSE_OPT_KEY_KEEP && ctx->proc) {
                int res = ctx->proc(ctx->data, arg, key, &ctx->outargs);
                if (res == -1 || !res)
                        return res;
        }
        if (iso)
                return add_opt(ctx, arg);
        else
                return add_arg(ctx, arg);
}

static int match_template(const char *t, const char *arg, unsigned *sepp)
{
        int arglen = strlen(arg);
        const char *sep = strchr(t, '=');
        sep = sep ? sep : strchr(t, ' ');
        if (sep && (!sep[1] || sep[1] == '%')) {
                int tlen = sep - t;
                if (sep[0] == '=')
                        tlen ++;
                if (arglen >= tlen && strncmp(arg, t, tlen) == 0) {
                        *sepp = sep - t;
                        return 1;
                }
        }
        if (strcmp(t, arg) == 0) {
                *sepp = 0;
                return 1;
        }
        return 0;
}

static const struct fuse_opt *find_opt(const struct fuse_opt *opt,
                                       const char *arg, unsigned *sepp)
{
        for (; opt && opt->templ; opt++)
                if (match_template(opt->templ, arg, sepp))
                        return opt;
        return NULL;
}

int fuse_opt_match(const struct fuse_opt *opts, const char *opt)
{
        unsigned dummy;
        return find_opt(opts, opt, &dummy) ? 1 : 0;
}

static int process_opt_param(void *var, const char *format, const char *param,
                             const char *arg)
{
        assert(format[0] == '%');
        if (format[1] == 's') {
                char **s = var;
                char *copy = strdup(param);
                if (!copy)
                        return alloc_failed();

                free(*s);
                *s = copy;
        } else {
                if (sscanf(param, format, var) != 1) {
                        fprintf(stderr, "fuse: invalid parameter in option `%s'\n", arg);
                        return -1;
                }
        }
        return 0;
}

static int process_opt(struct fuse_opt_context *ctx,
                       const struct fuse_opt *opt, unsigned sep,
                       const char *arg, int iso)
{
        if (opt->offset == -1U) {
                if (call_proc(ctx, arg, opt->value, iso) == -1)
                        return -1;
        } else {
                void *var = (char *)ctx->data + opt->offset;
                if (sep && opt->templ[sep + 1]) {
                        const char *param = arg + sep;
                        if (opt->templ[sep] == '=')
                                param ++;
                        if (process_opt_param(var, opt->templ + sep + 1,
                                              param, arg) == -1)
                                return -1;
                } else
                        *(int *)var = opt->value;
        }
        return 0;
}

static int process_opt_sep_arg(struct fuse_opt_context *ctx,
                               const struct fuse_opt *opt, unsigned sep,
                               const char *arg, int iso)
{
        int res;
        char *newarg;
        char *param;

        if (next_arg(ctx, arg) == -1)
                return -1;

        param = ctx->argv[ctx->argctr];
        newarg = malloc(sep + strlen(param) + 1);
        if (!newarg)
                return alloc_failed();

        memcpy(newarg, arg, sep);
        strcpy(newarg + sep, param);
        res = process_opt(ctx, opt, sep, newarg, iso);
        free(newarg);

        return res;
}

static int process_gopt(struct fuse_opt_context *ctx, const char *arg, int iso)
{
        unsigned sep;
        const struct fuse_opt *opt = find_opt(ctx->opt, arg, &sep);
        if (opt) {
                for (; opt; opt = find_opt(opt + 1, arg, &sep)) {
                        int res;
                        if (sep && opt->templ[sep] == ' ' && !arg[sep])
                                res = process_opt_sep_arg(ctx, opt, sep, arg,
                                                          iso);
                        else
                                res = process_opt(ctx, opt, sep, arg, iso);
                        if (res == -1)
                                return -1;
                }
                return 0;
        } else
                return call_proc(ctx, arg, FUSE_OPT_KEY_OPT, iso);
}

static int process_real_option_group(struct fuse_opt_context *ctx, char *opts)
{
        char *s = opts;
        char *d = s;
        int end = 0;

        while (!end) {
                if (*s == '\0')
                        end = 1;
                if (*s == ',' || end) {
                        int res;

                        *d = '\0';
                        res = process_gopt(ctx, opts, 1);
                        if (res == -1)
                                return -1;
                        d = opts;
                } else {
                        if (s[0] == '\\' && s[1] != '\0') {
                                s++;
                                if (s[0] >= '0' && s[0] <= '3' &&
                                    s[1] >= '0' && s[1] <= '7' &&
                                    s[2] >= '0' && s[2] <= '7') {
                                        *d++ = (s[0] - '0') * 0100 +
                                                (s[1] - '0') * 0010 +
                                                (s[2] - '0');
                                        s += 2;
                                } else {
                                        *d++ = *s;
                                }
                        } else {
                                *d++ = *s;
                        }
                }
                s++;
        }

        return 0;
}

static int process_option_group(struct fuse_opt_context *ctx, const char *opts)
{
        int res;
        char *copy = strdup(opts);

        if (!copy) {
                fprintf(stderr, "fuse: memory allocation failed\n");
                return -1;
        }
        res = process_real_option_group(ctx, copy);
        free(copy);
        return res;
}

static int process_one(struct fuse_opt_context *ctx, const char *arg)
{
        if (ctx->nonopt || arg[0] != '-')
                return call_proc(ctx, arg, FUSE_OPT_KEY_NONOPT, 0);
        else if (arg[1] == 'o') {
                if (arg[2])
                        return process_option_group(ctx, arg + 2);
                else {
                        if (next_arg(ctx, arg) == -1)
                                return -1;

                        return process_option_group(ctx,
                                                    ctx->argv[ctx->argctr]);
                }
        } else if (arg[1] == '-' && !arg[2]) {
                if (add_arg(ctx, arg) == -1)
                        return -1;
                ctx->nonopt = ctx->outargs.argc;
                return 0;
        } else
                return process_gopt(ctx, arg, 0);
}

static int opt_parse(struct fuse_opt_context *ctx)
{
        if (ctx->argc) {
                if (add_arg(ctx, ctx->argv[0]) == -1)
                        return -1;
        }

        for (ctx->argctr = 1; ctx->argctr < ctx->argc; ctx->argctr++)
                if (process_one(ctx, ctx->argv[ctx->argctr]) == -1)
                        return -1;

        if (ctx->opts) {
                if (fuse_opt_insert_arg(&ctx->outargs, 1, "-o") == -1 ||
                    fuse_opt_insert_arg(&ctx->outargs, 2, ctx->opts) == -1)
                        return -1;
        }

        /* If option separator ("--") is the last argument, remove it */
        if (ctx->nonopt && ctx->nonopt == ctx->outargs.argc &&
            strcmp(ctx->outargs.argv[ctx->outargs.argc - 1], "--") == 0) {
                free(ctx->outargs.argv[ctx->outargs.argc - 1]);
                ctx->outargs.argv[--ctx->outargs.argc] = NULL;
        }

        return 0;
}

int fuse_opt_parse(struct fuse_args *args, void *data,
                   const struct fuse_opt opts[], fuse_opt_proc_t proc)
{
        int res;
        struct fuse_opt_context ctx = {
                .data = data,
                .opt = opts,
                .proc = proc,
        };

        if (!args || !args->argv || !args->argc)
                return 0;

        ctx.argc = args->argc;
        ctx.argv = args->argv;

        res = opt_parse(&ctx);
        if (res != -1) {
                struct fuse_args tmp = *args;
                *args = ctx.outargs;
                ctx.outargs = tmp;
        }
        free(ctx.opts);
        fuse_opt_free_args(&ctx.outargs);
        return res;
}