configfile.c

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/*      config_read(), _delete(), _length() - Generic config file routines.
 *                                                      Author: Kees J. Bot
 *                                                              5 Jun 1999
 */
#define nil ((void*)0)
#if __minix_vmd
#include <minix/stubs.h>
#else
#define fstat _fstat
#define stat _stat
#endif
#include <sys/types.h>
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include <sys/stat.h>
#if __minix_vmd
#include <minix/asciictype.h>
#else
#include <ctype.h>
#endif
#define _c /* not const */
#include <configfile.h>

typedef struct configfile {     /* List of (included) configuration files. */
        struct configfile *next;        /* A list indeed. */
        time_t          ctime;          /* Last changed time, -1 if no file. */
        char            name[1];        /* File name. */
} configfile_t;

/* Size of a configfile_t given a file name of length 'len'. */
#define configfilesize(len)     (offsetof(configfile_t, name) + 1 + (len))

typedef struct firstconfig {    /* First file and first word share a slot. */
        configfile_t    *filelist;
        char            new;            /* Set when created. */
        config_t        config1;
} firstconfig_t;

/* Size of a config_t given a word of lenght 'len'.  Same for firstconfig_t. */
#define config0size()           (offsetof(config_t, word))
#define configsize(len)         (config0size() + 1 + (len))
#define firstconfigsize(len)    \
                        (offsetof(firstconfig_t, config1) + configsize(len))

/* Translate address of first config word to enclosing firstconfig_t and vv. */
#define cfg2fcfg(p)     \
    ((firstconfig_t *) ((char *) (p) - offsetof(firstconfig_t, config1)))
#define fcfg2cfg(p)     (&(p)->config1)

/* Variables used while building data. */
static configfile_t *c_files;           /* List of (included) config files. */
static int c_flags;                     /* Flags argument of config_read(). */
static FILE *c_fp;                      /* Current open file. */
static char *c_file;                    /* Current open file name. */
static unsigned c_line;                 /* Current line number. */
static int c;                           /* Next character. */

static void *allocate(void *mem, size_t size)
/* Like realloc(), but checked. */
{
    if ((mem= realloc(mem, size)) == nil) {
        fprintf(stderr, "\"%s\", line %u: Out of memory\n", c_file, c_line);
        exit(1);
    }
    return mem;
}

#define deallocate(mem) free(mem)

static void delete_filelist(configfile_t *cfgf)
/* Delete configuration file list. */
{
    void *junk;

    while (cfgf != nil) {
        junk= cfgf;
        cfgf= cfgf->next;
        deallocate(junk);
    }
}

static void delete_config(config_t *cfg)
/* Delete configuration file data. */
{
    config_t *next, *list, *junk;

    next= cfg;
    list= nil;
    for (;;) {
        if (next != nil) {
            /* Push the 'next' chain in reverse on the 'list' chain, putting
             * a leaf cell (next == nil) on top of 'list'.
             */
            junk= next;
            next= next->next;
            junk->next= list;
            list= junk;
        } else
        if (list != nil) {
            /* Delete the leaf cell.  If it has a sublist then that becomes
             * the 'next' chain.
             */
            junk= list;
            next= list->list;
            list= list->next;
            deallocate(junk);
        } else {
            /* Both chains are gone. */
            break;
        }
    }
}

void config_delete(config_t *cfg1)
/* Delete configuration file data, being careful with the odd first one. */
{
    firstconfig_t *fcfg= cfg2fcfg(cfg1);

    delete_filelist(fcfg->filelist);
    delete_config(fcfg->config1.next);
    delete_config(fcfg->config1.list);
    deallocate(fcfg);
}

static void nextc(void)
/* Read the next character of the current file into 'c'. */
{
    if (c == '\n') c_line++;
    c= getc(c_fp);
    if (c == EOF && ferror(c_fp)) {
        fprintf(stderr, "\"%s\", line %u: %s\n",
            c_file, c_line, strerror(errno));
        exit(1);
    }
}

static void skipwhite(void)
/* Skip whitespace and comments. */
{
    while (isspace(c)) {
        nextc();
        if (c == '#') {
            do nextc(); while (c != EOF && c != '\n');
        }
    }
}

static void parse_err(void)
/* Tell user that you can't parse past the current character. */
{
    char sc[2];

    sc[0]= c;
    sc[1]= 0;
    fprintf(stderr, "\"%s\", line %u: parse error at '%s'\n",
        c_file, c_line, c == EOF ? "EOF" : sc);
    exit(1);
}

static config_t *read_word(void)
/* Read a word or string. */
{
    config_t *w;
    size_t i, len;
    int q;
    static char SPECIAL[] = "!#$%&*+-./:<=>?[\\]^_|~";

    i= 0;
    len= 32;
    w= allocate(nil, configsize(32));
    w->next= nil;
    w->list= nil;
    w->file= c_file;
    w->line= c_line;
    w->flags= 0;

    /* Is it a quoted string? */
    if (c == '\'' || c == '"') {
        q= c;   /* yes */
        nextc();
    } else {
        q= -1;  /* no */
    }

    for (;;) {
        if (i == len) {
            len+= 32;
            w= allocate(w, configsize(len));
        }

        if (q == -1) {
            /* A word consists of letters, numbers and a few special chars. */
            if (!isalnum(c) && c < 0x80 && strchr(SPECIAL, c) == nil) break;
        } else {
            /* Strings are made up of anything except newlines. */
            if (c == EOF || c == '\n') {
                fprintf(stderr,
                    "\"%s\", line %u: string at line %u not closed\n",
                    c_file, c_line, w->line);
                exit(1);
                break;
            }
            if (c == q) {       /* Closing quote? */
                nextc();
                break;
            }
        }

        if (c != '\\') {        /* Simply add non-escapes. */
            w->word[i++]= c;
            nextc();
        } else {                /* Interpret an escape. */
            nextc();
            if (isspace(c)) {
                skipwhite();
                continue;
            }

            if (c_flags & CFG_ESCAPED) {
                w->word[i++]= '\\';     /* Keep the \ for the caller. */
                if (i == len) {
                    len+= 32;
                    w= allocate(w, configsize(len));
                }
                w->flags |= CFG_ESCAPED;
            }

            if (isdigit(c)) {           /* Octal escape */
                int n= 3;
                int d= 0;

                do {
                    d= d * 010 + (c - '0');
                    nextc();
                } while (--n > 0 && isdigit(c));
                w->word[i++]= d;
            } else
            if (c == 'x' || c == 'X') { /* Hex escape */
                int n= 2;
                int d= 0;

                nextc();
                if (!isxdigit(c)) {
                    fprintf(stderr, "\"%s\", line %u: bad hex escape\n",
                        c_file, c_line);
                    exit(1);
                }
                do {
                    d= d * 0x10 + (islower(c) ? (c - 'a' + 0xa) :
                                    isupper(c) ? (c - 'A' + 0xA) :
                                    (c - '0'));
                    nextc();
                } while (--n > 0 && isxdigit(c));
                w->word[i++]= d;
            } else {
                switch (c) {
                case 'a':       c= '\a';        break;
                case 'b':       c= '\b';        break;
                case 'e':       c= '\033';      break;
                case 'f':       c= '\f';        break;
                case 'n':       c= '\n';        break;
                case 'r':       c= '\r';        break;
                case 's':       c= ' ';         break;
                case 't':       c= '\t';        break;
                case 'v':       c= '\v';        break;
                default:        /* Anything else is kept as-is. */;
                }
                w->word[i++]= c;
                nextc();
            }
        }
    }
    w->word[i]= 0;
    if (q != -1) {
        w->flags |= CFG_STRING;
    } else {
        int f;
        char *end;
        static char base[]= { 0, 010, 10, 0x10 };

        if (i == 0) parse_err();

        /* Can the word be used as a number? */
        for (f= 0; f < 4; f++) {
            (void) strtol(w->word, &end, base[f]);
            if (*end == 0) w->flags |= 1 << (f + 0);
            (void) strtoul(w->word, &end, base[f]);
            if (*end == 0) w->flags |= 1 << (f + 4);
        }
    }
    return allocate(w, configsize(i));
}

static config_t *read_file(const char *file);
static config_t *read_list(void);

static config_t *read_line(void)
/* Read and return one line of the config file. */
{
    config_t *cline, **pcline, *clist;

    cline= nil;
    pcline= &cline;

    for (;;) {
        skipwhite();

        if (c == EOF || c == '}') {
if(0)       if (cline != nil) parse_err();
            break;
        } else
        if (c == ';') {
            nextc();
            if (cline != nil) break;
        } else
        if (cline != nil && c == '{') {
            /* A sublist. */
            nextc();
            clist= allocate(nil, config0size());
            clist->next= nil;
            clist->file= c_file;
            clist->line= c_line;
            clist->list= read_list();
            clist->flags= CFG_SUBLIST;
            *pcline= clist;
            pcline= &clist->next;
            if (c != '}') parse_err();
            nextc();
        } else {
            *pcline= read_word();
            pcline= &(*pcline)->next;
        }
    }
    return cline;
}

static config_t *read_list(void)
/* Read and return a list of config file commands. */
{
    config_t *clist, **pclist, *cline;

    clist= nil;
    pclist= &clist;

    while ((cline= read_line()) != nil) {
        if (strcmp(cline->word, "include") == 0) {
            config_t *file= cline->next;
            if (file == nil || file->next != nil || !config_isatom(file)) {
                fprintf(stderr,
                    "\"%s\", line %u: 'include' command requires an argument\n",
                    c_file, cline->line);
                exit(1);
            }
            if (file->flags & CFG_ESCAPED) {
                char *p, *q;
                p= q= file->word;
                for (;;) {
                    if ((*q = *p) == '\\') *q = *++p;
                    if (*q == 0) break;
                    p++;
                    q++;
                }
            }
            file= read_file(file->word);
            delete_config(cline);
            *pclist= file;
            while (*pclist != nil) pclist= &(*pclist)->next;
        } else {
            config_t *cfg= allocate(nil, config0size());
            cfg->next= nil;
            cfg->list= cline;
            cfg->file= cline->file;
            cfg->line= cline->line;
            cfg->flags= CFG_SUBLIST;
            *pclist= cfg;
            pclist= &cfg->next;
        }
    }
    return clist;
}

static config_t *read_file(const char *file)
/* Read and return a configuration file. */
{
    configfile_t *cfgf;
    config_t *cfg;
    struct stat st;
    FILE *old_fp;       /* old_* variables store current file context. */
    char *old_file;
    unsigned old_line;
    int old_c;
    size_t n;
    char *slash;

    old_fp= c_fp;
    old_file= c_file;
    old_line= c_line;
    old_c= c;

    n= 0;
    if (file[0] != '/' && old_file != nil
                        && (slash= strrchr(old_file, '/')) != nil) {
        n= slash - old_file + 1;
    }
    cfgf= allocate(nil, configfilesize(n + strlen(file)));
    memcpy(cfgf->name, old_file, n);
    strcpy(cfgf->name + n, file);
    cfgf->next= c_files;
    c_files= cfgf;

    c_file= cfgf->name;
    c_line= 0;

    if ((c_fp= fopen(file, "r")) == nil || fstat(fileno(c_fp), &st) < 0) {
        if (errno != ENOENT) {
            fprintf(stderr, "\"%s\", line 1: %s\n", file, strerror(errno));
            exit(1);
        }
        cfgf->ctime= -1;
        c= EOF;
    } else {
        cfgf->ctime= st.st_ctime;
        c= '\n';
    }

    cfg= read_list();
    if (c != EOF) parse_err();

    if (c_fp != nil) fclose(c_fp);
    c_fp= old_fp;
    c_file= old_file;
    c_line= old_line;
    c= old_c;
    return cfg;
}

config_t *config_read(const char *file, int flags, config_t *cfg)
/* Read and parse a configuration file. */
{
    if (cfg != nil) {
        /* First check if any of the involved files has changed. */
        firstconfig_t *fcfg;
        configfile_t *cfgf;
        struct stat st;

        fcfg= cfg2fcfg(cfg);
        for (cfgf= fcfg->filelist; cfgf != nil; cfgf= cfgf->next) {
            if (stat(cfgf->name, &st) < 0) {
                if (errno != ENOENT) break;
                st.st_ctime= -1;
            }
            if (st.st_ctime != cfgf->ctime) break;
        }

        if (cfgf == nil) return cfg;    /* Everything as it was. */
        config_delete(cfg);             /* Otherwise delete and reread. */
    }

    errno= 0;
    c_files= nil;
    c_flags= flags;
    cfg= read_file(file);

    if (cfg != nil) {
        /* Change first word to have a hidden pointer to a file list. */
        size_t len= strlen(cfg->word);
        firstconfig_t *fcfg;

        fcfg= allocate(cfg, firstconfigsize(len));
        memmove(&fcfg->config1, fcfg, configsize(len));
        fcfg->filelist= c_files;
        fcfg->new= 1;
        return fcfg2cfg(fcfg);
    }
    /* Couldn't read (errno != 0) of nothing read (errno == 0). */
    delete_filelist(c_files);
    delete_config(cfg);
    return nil;
}

int config_renewed(config_t *cfg)
{
    int new;

    if (cfg == nil) {
        new= 1;
    } else {
        new= cfg2fcfg(cfg)->new;
        cfg2fcfg(cfg)->new= 0;
    }
    return new;
}

size_t config_length(config_t *cfg)
/* Count the number of items on a list. */
{
    size_t n= 0;

    while (cfg != nil) {
        n++;
        cfg= cfg->next;
    }
    return n;
}

#if TEST
#include <unistd.h>

static void print_list(int indent, config_t *cfg);

static void print_words(int indent, config_t *cfg)
{
    while (cfg != nil) {
        if (config_isatom(cfg)) {
            if (config_isstring(cfg)) fputc('"', stdout);
            printf("%s", cfg->word);
            if (config_isstring(cfg)) fputc('"', stdout);
        } else {
            printf("{\n");
            print_list(indent+4, cfg->list);
            printf("%*s}", indent, "");
        }
        cfg= cfg->next;
        if (cfg != nil) fputc(' ', stdout);
    }
    printf(";\n");
}

static void print_list(int indent, config_t *cfg)
{
    while (cfg != nil) {
        if (!config_issub(cfg)) {
            fprintf(stderr, "Cell at \"%s\", line %u is not a sublist\n");
            break;
        }
        printf("%*s", indent, "");
        print_words(indent, cfg->list);
        cfg= cfg->next;
    }
}

static void print_config(config_t *cfg)
{
    if (!config_renewed(cfg)) {
        printf("# Config didn't change\n");
    } else {
        print_list(0, cfg);
    }
}

int main(int argc, char **argv)
{
    config_t *cfg;
    int c;

    if (argc != 2) {
        fprintf(stderr, "One config file name please\n");
        exit(1);
    }

    cfg= nil;
    do {
        cfg= config_read(argv[1], CFG_ESCAPED, cfg);
        print_config(cfg);
        if (!isatty(0)) break;
        while ((c= getchar()) != EOF && c != '\n') {}
    } while (c != EOF);
    return 0;
}
#endif /* TEST */

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