busybox/scripts/bb_mkdep.c
"Vladimir N. Oleynik" d128b71820 speed up * 2
2005-10-03 10:08:46 +00:00

935 lines
22 KiB
C

/*
* Another fast dependencies generator for Makefiles, Version 2.3
*
* Copyright (C) 2005 by Vladimir Oleynik <dzo@simtreas.ru>
* mmaping file may be originally by Linus Torvalds.
*
* (c) 2005 Bernhard Fischer:
* - commentary typos,
* - move "memory exhausted" into msg_enomem,
* - more verbose --help output.
*
* This program does:
* 1) find #define KEY VALUE or #undef KEY from include/config.h
* 2) save include/config/key*.h if changed after previous usage
* 3) recursive scan from "./" *.[ch] files, but skips scan of include/config/
* 4) find #include "*.h" and KEYs using, if not as #define and #undef
* 5) generate dependencies to stdout
* path/file.o: include/config/key*.h found_include_*.h
* path/inc.h: include/config/key*.h found_included_include_*.h
* This program does not generate dependencies for #include <...>
* BUG: all includes name must unique
*/
#define LOCAL_INCLUDE_PATH "include"
#define INCLUDE_CONFIG_PATH LOCAL_INCLUDE_PATH"/config"
#define INCLUDE_CONFIG_KEYS_PATH LOCAL_INCLUDE_PATH"/config.h"
#define bb_mkdep_full_options \
"\nOptions:" \
"\n\t-I local_include_path include paths, default: \"" LOCAL_INCLUDE_PATH "\"" \
"\n\t-d don't generate depend" \
"\n\t-w show warning if include files not found" \
"\n\t-k include/config default: \"" INCLUDE_CONFIG_PATH "\"" \
"\n\t-c include/config.h configs, default: \"" INCLUDE_CONFIG_KEYS_PATH "\"" \
"\n\tdirs_to_scan default \".\""
#define bb_mkdep_terse_options "Usage: [-I local_include_paths] [-dw] " \
"[-k path_for_stored_keys] [dirs]"
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <getopt.h>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
typedef struct BB_KEYS {
char *keyname;
size_t key_sz;
const char *value;
char *stored_path;
char *checked;
struct BB_KEYS *next;
} bb_key_t;
static bb_key_t *check_key(bb_key_t *k, const char *nk, size_t key_sz);
static bb_key_t *make_new_key(bb_key_t *k, const char *nk, size_t key_sz);
/* partial and simplified libbb routine */
static void bb_error_d(const char *s, ...) __attribute__ ((noreturn, format (printf, 1, 2)));
static char * bb_asprint(const char *format, ...) __attribute__ ((format (printf, 1, 2)));
/* stolen from libbb as is */
typedef struct llist_s {
char *data;
struct llist_s *link;
} llist_t;
static void *xrealloc(void *p, size_t size);
static void *xmalloc(size_t size);
static char *bb_xstrdup(const char *s);
static char *bb_simplify_path(const char *path);
/* error messages */
static const char msg_enomem[] = "memory exhausted";
/* for lexical analyser */
static bb_key_t *key_top;
static llist_t *configs;
static int mode;
#define CONFIG_MODE 0
#define SOURCES_MODE 1
static void parse_inc(const char *include, const char *fname, size_t key_sz);
static void parse_conf_opt(const char *opt, const char *val,
size_t rsz, size_t key_sz);
/* for speed tricks */
static char first_chars[257]; /* + L_EOF */
static char isalnums[257]; /* + L_EOF */
/* trick for fast find "define", "include", "undef" */
static char first_chars_diu[256];
static int pagesizem1;
static size_t mema_id = 128; /* first allocated for id */
static char *id_s;
#define yy_error_d(s) bb_error_d("%s:%d hmm, %s", fname, line, s)
/* state */
#define S 0 /* start state */
#define STR '"' /* string */
#define CHR '\'' /* char */
#define REM '/' /* block comment */
#define BS '\\' /* back slash */
#define POUND '#' /* # */
#define I 'i' /* #include preprocessor's directive */
#define D 'd' /* #define preprocessor's directive */
#define U 'u' /* #undef preprocessor's directive */
#define LI 'I' /* #include "... */
#define DK 'K' /* #define KEY... (config mode) */
#define DV 'V' /* #define KEY "VALUE or #define KEY 'VALUE */
#define NLC 'n' /* \ and \n */
#define ANY '*' /* any unparsed chars */
#define L_EOF 256
/* [A-Z_a-z] */
#define ID(c) ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || c == '_')
/* [A-Z_a-z0-9] */
#define ISALNUM(c) (ID(c) || (c >= '0' && c <= '9'))
#define getc1() do { c = (optr >= oend) ? L_EOF : *optr++; } while(0)
#define ungetc1() optr--
#define put_id(c) do { if(id_len == local_mema_id) \
id = xrealloc(id, local_mema_id += 16); \
id[id_len++] = c; } while(0)
/* stupid C lexical analyser */
static void c_lex(const char *fname, long fsize)
{
int c = L_EOF; /* stupid initialize */
int prev_state = L_EOF;
int called;
int state;
int line;
char *id = id_s;
size_t local_mema_id = mema_id;
size_t id_len = 0; /* stupid initialize */
char *val = NULL;
unsigned char *optr, *oend;
unsigned char *start = NULL; /* stupid initialize */
size_t opt_len = 0; /* stupid initialize */
int fd;
char *map;
int mapsize;
if(fsize == 0) {
fprintf(stderr, "Warning: %s is empty\n", fname);
return;
}
fd = open(fname, O_RDONLY);
if(fd < 0) {
perror(fname);
return;
}
mapsize = (fsize+pagesizem1) & ~pagesizem1;
map = mmap(NULL, mapsize, PROT_READ, MAP_PRIVATE, fd, 0);
if ((long) map == -1)
bb_error_d("%s: mmap: %m", fname);
optr = (unsigned char *)map;
oend = optr + fsize;
line = 1;
called = state = S;
for(;;) {
if(prev_state != state) {
prev_state = state;
getc1();
}
/* [ \t]+ eat first space */
while(c == ' ' || c == '\t')
getc1();
if(c == BS) {
getc1();
if(c == '\n') {
/* \\\n eat continued */
line++;
prev_state = NLC;
continue;
}
ungetc1();
c = BS;
}
if(state == S) {
while(first_chars[c] == ANY) {
/* <S>unparsed */
if(c == '\n')
line++;
getc1();
}
if(c == L_EOF) {
/* <S><<EOF>> */
id_s = id;
mema_id = local_mema_id;
munmap(map, mapsize);
close(fd);
return;
}
if(c == REM) {
/* <S>/ */
getc1(); /* eat <S>/ */
if(c == REM) {
/* <S>"//"[^\n]* */
do getc1(); while(c != '\n' && c != L_EOF);
} else if(c == '*') {
/* <S>[/][*] */
called = S;
state = REM;
}
} else if(c == POUND) {
/* <S># */
start = optr - 1;
state = c;
} else if(c == STR || c == CHR) {
/* <S>\"|\' */
val = NULL;
called = S;
state = c;
} else if(c != BS) {
/* <S>[A-Z_a-z0-9] */
/* trick for fast drop id
if key with this first char undefined */
if(first_chars[c] == 0) {
/* skip <S>[A-Z_a-z0-9]+ */
do getc1(); while(isalnums[c]);
} else {
id_len = 0;
do {
/* <S>[A-Z_a-z0-9]+ */
put_id(c);
getc1();
} while(isalnums[c]);
check_key(key_top, id, id_len);
}
} else {
/* <S>\\ */
prev_state = c;
}
continue;
}
if(state == REM) {
for(;;) {
/* <REM>[^*]+ */
while(c != '*') {
if(c == '\n') {
/* <REM>\n */
if(called != S)
yy_error_d("unexpected newline");
line++;
} else if(c == L_EOF)
yy_error_d("unexpected EOF");
getc1();
}
/* <REM>[*] */
getc1();
if(c == REM) {
/* <REM>[*][/] */
state = called;
break;
}
}
continue;
}
if(state == STR || state == CHR) {
for(;;) {
/* <STR,CHR>\n|<<EOF>> */
if(c == '\n' || c == L_EOF)
yy_error_d("unterminated");
if(c == BS) {
/* <STR,CHR>\\ */
getc1();
if(c != BS && c != '\n' && c != state) {
/* another usage \ in str or char */
if(c == L_EOF)
yy_error_d("unexpected EOF");
if(val)
put_id(c);
continue;
}
/* <STR,CHR>\\[\\\n] or <STR>\\\" or <CHR>\\\' */
/* eat 2 char */
if(c == '\n')
line++;
else if(val)
put_id(c);
} else if(c == state) {
/* <STR>\" or <CHR>\' */
if(called == LI) {
/* store "include.h" */
parse_inc(id, fname, id_len);
} else if(called == DV) {
put_id(c); /* config mode #define KEY "VAL"<- */
put_id(0);
parse_conf_opt(id, val, (optr - start), opt_len);
}
state = S;
break;
} else if(val)
put_id(c);
/* <STR,CHR>. */
getc1();
}
continue;
}
/* begin preprocessor states */
if(c == L_EOF)
yy_error_d("unexpected EOF");
if(c == REM) {
/* <#.*>/ */
getc1();
if(c == REM)
yy_error_d("detected // in preprocessor line");
if(c == '*') {
/* <#.*>[/][*] */
called = state;
state = REM;
continue;
}
/* hmm, #.*[/] */
yy_error_d("strange preprocessor line");
}
if(state == POUND) {
/* tricks */
static const char * const preproc[] = {
/* 0-3 */
"", "", "", "",
/* 4 */ /* 5 */ /* 6 */
"ndef", "efine", "nclude",
};
size_t diu = first_chars_diu[c]; /* strlen and preproc ptr */
const unsigned char *p = optr;
while(isalnums[c]) getc1();
/* have str begined with c, readed == strlen key and compared */
if(diu != S && diu == (optr-p-1) && !memcmp(p, preproc[diu], diu)) {
state = p[-1];
id_len = 0; /* common for save */
} else {
state = S;
}
ungetc1();
continue;
}
if(state == I) {
if(c == STR) {
/* <I>\" */
val = id;
called = LI;
state = STR;
} else {
/* another (may be wrong) #include ... */
ungetc1();
state = S;
}
continue;
}
if(state == D || state == U) {
if(mode == SOURCES_MODE) {
/* ignore depend with #define or #undef KEY */
while(isalnums[c])
getc1();
state = S;
} else {
/* save KEY from #"define"|"undef" ... */
while(isalnums[c]) {
put_id(c);
getc1();
}
if(!id_len)
yy_error_d("expected identifier");
if(state == U) {
parse_conf_opt(id, NULL, (optr - start), id_len);
state = S;
} else {
/* D -> DK */
opt_len = id_len;
state = DK;
}
}
ungetc1();
continue;
}
if(state == DK) {
/* #define KEY[ ] (config mode) */
val = id + id_len;
if(c == STR || c == CHR) {
/* define KEY "... or define KEY '... */
put_id(c);
called = DV;
state = c;
continue;
}
while(isalnums[c]) {
/* VALUE */
put_id(c);
getc1();
}
put_id(0);
parse_conf_opt(id, val, (optr - start), opt_len);
state = S;
ungetc1();
continue;
}
}
}
static void show_usage(void) __attribute__ ((noreturn));
static void show_usage(void)
{
bb_error_d("%s\n%s\n", bb_mkdep_terse_options, bb_mkdep_full_options);
}
static const char *kp;
static size_t kp_len;
static llist_t *Iop;
static bb_key_t *Ifound;
static int noiwarning;
static bb_key_t *check_key(bb_key_t *k, const char *nk, size_t key_sz)
{
bb_key_t *cur;
for(cur = k; cur; cur = cur->next) {
if(key_sz == cur->key_sz && memcmp(cur->keyname, nk, key_sz) == 0) {
cur->checked = cur->stored_path;
return cur;
}
}
return NULL;
}
static bb_key_t *make_new_key(bb_key_t *k, const char *nk, size_t key_sz)
{
bb_key_t *cur;
cur = xmalloc(sizeof(bb_key_t) + key_sz + 1);
cur->keyname = memcpy(cur + 1, nk, key_sz);
cur->keyname[key_sz] = '\0';
cur->key_sz = key_sz;
cur->checked = NULL;
cur->next = k;
return cur;
}
static inline char *store_include_fullpath(char *p_i, bb_key_t *li)
{
char *ok;
if(access(p_i, F_OK) == 0) {
ok = li->stored_path = bb_simplify_path(p_i);
li->checked = ok;
} else {
ok = NULL;
}
free(p_i);
return ok;
}
static void parse_inc(const char *include, const char *fname, size_t key_sz)
{
bb_key_t *li;
char *p_i;
llist_t *lo;
li = check_key(Ifound, include, key_sz);
if(li)
return;
Ifound = li = make_new_key(Ifound, include, key_sz);
include = li->keyname;
if(include[0] != '/') {
/* relative */
int w;
p_i = strrchr(fname, '/'); /* fname have absolute pathname */
w = (p_i-fname);
/* find from current directory of source file */
p_i = bb_asprint("%.*s/%s", w, fname, include);
if(store_include_fullpath(p_i, li))
return;
/* find from "-I include" specified directories */
for(lo = Iop; lo; lo = lo->link) {
p_i = bb_asprint("%s/%s", lo->data, include);
if(store_include_fullpath(p_i, li))
return;
}
} else {
/* absolute include pathname */
if(access(include, F_OK) == 0) {
li->checked = li->stored_path = bb_xstrdup(include);
return;
}
}
li->stored_path = NULL;
if(noiwarning)
fprintf(stderr, "%s: Warning: #include \"%s\" not found in specified paths\n", fname, include);
}
static void parse_conf_opt(const char *opt, const char *val,
size_t recordsz, size_t key_sz)
{
bb_key_t *cur;
char *k;
char *s, *p;
struct stat st;
int fd;
int cmp_ok = 0;
static char *record_buf;
static size_t r_sz;
ssize_t rw_ret;
cur = check_key(key_top, opt, key_sz);
if(cur != NULL) {
/* present already */
cur->checked = NULL; /* store only */
if(cur->value == NULL && val == NULL)
return;
if(cur->value != NULL && val != NULL && !strcmp(cur->value, val))
return;
k = cur->keyname;
fprintf(stderr, "Warning: redefined %s\n", k);
} else {
key_top = cur = make_new_key(key_top, opt, key_sz);
k = cur->keyname;
}
/* do generate record */
recordsz += 2; /* \n\0 */
if(recordsz > r_sz)
record_buf = xrealloc(record_buf, (r_sz = recordsz) * 2);
s = record_buf;
/* may be short count " " */
if(val) {
if(*val == '\0') {
cur->value = "";
recordsz = sprintf(s, "#define %s\n", k);
} else {
cur->value = bb_xstrdup(val);
recordsz = sprintf(s, "#define %s %s\n", k, val);
}
} else {
cur->value = NULL;
recordsz = sprintf(s, "#undef %s\n", k);
}
/* size_t -> ssize_t :( */
rw_ret = (ssize_t)recordsz;
/* trick, save first char KEY for do fast identify id */
first_chars[(int)*k] = *k;
cur->stored_path = k = bb_asprint("%s/%s.h", kp, k);
/* key converting [A-Z_] -> [a-z/] */
for(p = k + kp_len + 1; *p; p++) {
if(*p >= 'A' && *p <= 'Z')
*p = *p - 'A' + 'a';
else if(*p == '_' && p[1] > '9') /* do not change A_1 to A/1 */
*p = '/';
}
/* check kp/key.h if present after previous usage */
if(stat(k, &st)) {
for(p = k + kp_len + 1; *p; p++) {
/* Auto-create directories. */
if (*p == '/') {
*p = '\0';
if (access(k, F_OK) != 0 && mkdir(k, 0755) != 0)
bb_error_d("mkdir(%s): %m", k);
*p = '/';
}
}
} else {
/* found */
if(st.st_size == (off_t)recordsz) {
char *r_cmp = s + recordsz;
fd = open(k, O_RDONLY);
if(fd < 0 || read(fd, r_cmp, recordsz) < rw_ret)
bb_error_d("%s: %m", k);
close(fd);
cmp_ok = memcmp(s, r_cmp, recordsz) == 0;
}
}
if(!cmp_ok) {
fd = open(k, O_WRONLY|O_CREAT|O_TRUNC, 0644);
if(fd < 0 || write(fd, s, recordsz) < rw_ret)
bb_error_d("%s: %m", k);
close(fd);
}
}
static int show_dep(int first, bb_key_t *k, const char *name)
{
bb_key_t *cur;
for(cur = k; cur; cur = cur->next) {
if(cur->checked) {
if(first) {
printf("\n%s:", name);
first = 0;
} else {
printf(" \\\n ");
}
printf(" %s", cur->checked);
}
cur->checked = NULL;
}
return first;
}
static struct stat st_kp;
static int dontgenerate_dep;
static char *
parse_chd(const char *fe, const char *p, size_t dirlen)
{
struct stat st;
char *fp;
size_t df_sz;
static char *dir_and_entry;
static size_t dir_and_entry_sz;
df_sz = dirlen + strlen(fe) + 2; /* dir/file\0 */
if(df_sz > dir_and_entry_sz)
dir_and_entry = xrealloc(dir_and_entry, dir_and_entry_sz = df_sz);
fp = dir_and_entry;
sprintf(fp, "%s/%s", p, fe);
if(stat(fp, &st)) {
fprintf(stderr, "Warning: stat(%s): %m\n", fp);
return NULL;
}
if(S_ISREG(st.st_mode)) {
llist_t *cfl;
char *e = fp + df_sz - 3;
if(*e++ != '.' || (*e != 'c' && *e != 'h')) {
/* direntry is regular file, but is not *.[ch] */
return NULL;
}
for(cfl = configs; cfl; cfl = cfl->link) {
struct stat *config = (struct stat *)cfl->data;
if (st.st_dev == config->st_dev && st.st_ino == config->st_ino) {
/* skip already parsed configs.h */
return NULL;
}
}
/* direntry is *.[ch] regular file and is not configs */
if(!dontgenerate_dep) {
int first;
c_lex(fp, st.st_size);
if(*e == 'c') {
/* *.c -> *.o */
*e = 'o';
}
first = show_dep(1, Ifound, fp);
first = show_dep(first, key_top, fp);
if(first == 0)
putchar('\n');
}
return NULL;
} else if(S_ISDIR(st.st_mode)) {
if (st.st_dev == st_kp.st_dev && st.st_ino == st_kp.st_ino)
return NULL; /* drop scan kp/ directory */
/* direntry is directory. buff is returned, begin of zero allocate */
dir_and_entry = NULL;
dir_and_entry_sz = 0;
return fp;
}
/* hmm, direntry is device! */
return NULL;
}
/* from libbb but inline for fast */
static inline llist_t *llist_add_to(llist_t *old_head, char *new_item)
{
llist_t *new_head;
new_head = xmalloc(sizeof(llist_t));
new_head->data = new_item;
new_head->link = old_head;
return(new_head);
}
static void scan_dir_find_ch_files(const char *p)
{
llist_t *dirs;
llist_t *d_add;
llist_t *d;
struct dirent *de;
DIR *dir;
size_t dirlen;
dirs = llist_add_to(NULL, bb_simplify_path(p));
/* emulate recursive */
while(dirs) {
d_add = NULL;
while(dirs) {
dir = opendir(dirs->data);
if (dir == NULL)
fprintf(stderr, "Warning: opendir(%s): %m\n", dirs->data);
dirlen = strlen(dirs->data);
while ((de = readdir(dir)) != NULL) {
char *found_dir;
if (de->d_name[0] == '.')
continue;
found_dir = parse_chd(de->d_name, dirs->data, dirlen);
if(found_dir)
d_add = llist_add_to(d_add, found_dir);
}
closedir(dir);
free(dirs->data);
d = dirs;
dirs = dirs->link;
free(d);
}
dirs = d_add;
}
}
static char *pwd;
int main(int argc, char **argv)
{
char *s;
int i;
llist_t *fl;
{
/* for bb_simplify_path */
/* libbb xgetcwd(), this program have not chdir() */
unsigned path_max = 512;
s = xmalloc (path_max);
#define PATH_INCR 32
while (getcwd (s, path_max) == NULL) {
if(errno != ERANGE)
bb_error_d("getcwd: %m");
s = xrealloc (s, path_max += PATH_INCR);
}
pwd = s;
}
while ((i = getopt(argc, argv, "I:c:dk:w")) > 0) {
switch(i) {
case 'I':
Iop = llist_add_to(Iop, optarg);
break;
case 'c':
s = bb_simplify_path(optarg);
configs = llist_add_to(configs, s);
break;
case 'd':
dontgenerate_dep = 1;
break;
case 'k':
if(kp)
bb_error_d("Hmm, why multiple -k?");
kp = bb_simplify_path(optarg);
break;
case 'w':
noiwarning = 1;
break;
default:
show_usage();
}
}
/* default kp */
if(kp == NULL)
kp = bb_simplify_path(INCLUDE_CONFIG_PATH);
/* globals initialize */
kp_len = strlen(kp);
if(stat(kp, &st_kp))
bb_error_d("stat(%s): %m", kp);
if(!S_ISDIR(st_kp.st_mode))
bb_error_d("%s is not directory", kp);
/* defaults */
if(Iop == NULL)
Iop = llist_add_to(Iop, LOCAL_INCLUDE_PATH);
if(configs == NULL) {
s = bb_simplify_path(INCLUDE_CONFIG_KEYS_PATH);
configs = llist_add_to(configs, s);
}
/* for c_lex */
pagesizem1 = getpagesize() - 1;
id_s = xmalloc(mema_id);
for(i = 0; i < 256; i++) {
if(ISALNUM(i))
isalnums[i] = i;
/* set unparsed chars for speed up of parser */
else if(i != CHR && i != STR && i != POUND && i != REM && i != BS)
first_chars[i] = ANY;
}
first_chars[i] = '-'; /* L_EOF */
/* trick for fast find "define", "include", "undef" */
first_chars_diu[(int)'d'] = (char)5; /* strlen("define") - 1; */
first_chars_diu[(int)'i'] = (char)6; /* strlen("include") - 1; */
first_chars_diu[(int)'u'] = (char)4; /* strlen("undef") - 1; */
/* parse configs */
for(fl = configs; fl; fl = fl->link) {
struct stat st;
if(stat(fl->data, &st))
bb_error_d("stat(%s): %m", fl->data);
c_lex(fl->data, st.st_size);
/* trick for fast comparing found files with configs */
fl->data = xrealloc(fl->data, sizeof(struct stat));
memcpy(fl->data, &st, sizeof(struct stat));
}
/* main loop */
mode = SOURCES_MODE;
argv += optind;
if(*argv) {
while(*argv)
scan_dir_find_ch_files(*argv++);
} else {
scan_dir_find_ch_files(".");
}
return 0;
}
/* partial and simplified libbb routine */
static void bb_error_d(const char *s, ...)
{
va_list p;
va_start(p, s);
vfprintf(stderr, s, p);
va_end(p);
putc('\n', stderr);
exit(1);
}
static char *bb_asprint(const char *format, ...)
{
va_list p;
int r;
char *out;
va_start(p, format);
r = vasprintf(&out, format, p);
va_end(p);
if (r < 0)
bb_error_d("bb_asprint: %m");
return out;
}
/* partial libbb routine as is */
static void *xmalloc(size_t size)
{
void *p = malloc(size);
if(p == NULL)
bb_error_d(msg_enomem);
return p;
}
static void *xrealloc(void *p, size_t size) {
p = realloc(p, size);
if(p == NULL)
bb_error_d(msg_enomem);
return p;
}
static char *bb_xstrdup(const char *s)
{
char *r = strdup(s);
if(r == NULL)
bb_error_d(msg_enomem);
return r;
}
static char *bb_simplify_path(const char *path)
{
char *s, *start, *p;
if (path[0] == '/')
start = bb_xstrdup(path);
else {
/* is not libbb, but this program have not chdir() */
start = bb_asprint("%s/%s", pwd, path);
}
p = s = start;
do {
if (*p == '/') {
if (*s == '/') { /* skip duplicate (or initial) slash */
continue;
} else if (*s == '.') {
if (s[1] == '/' || s[1] == 0) { /* remove extra '.' */
continue;
} else if ((s[1] == '.') && (s[2] == '/' || s[2] == 0)) {
++s;
if (p > start) {
while (*--p != '/'); /* omit previous dir */
}
continue;
}
}
}
*++p = *s;
} while (*++s);
if ((p == start) || (*p != '/')) { /* not a trailing slash */
++p; /* so keep last character */
}
*p = 0;
return start;
}