This little patch does nothing with the functionality of devfsd, but
with the C code. There are a number of constructions like:
[PFXLEN = strlen(prefix);]
if (strncmp(str, prefix, PFXLEN) == 0)
do_something_with(str + PFXLEN);
It is not the best way to do such a things. The idea is to implement
the special function, which will test the string for some prefix and
return the address of a place of the string after that prefix or NULL
in case of an absence of the success. The construction above becomes
better:
if (ptr= strtry(str, prefix))
do_something_with(ptr);
And the new function itself is more lightweight than alone strncmp,
and just much more effective than <strlen + strncmp> in a couple. It
is good again. So, all the idea seems to be healthy. I've called
this function "strtry", as it tries its arg for the given prefix.
Richard, please, apply this patch, if you find it useful. It is
against devfsd-1.3.22. By the way, I've arranged the
strrchr (devname, '/') + 1
stuff, so this thing to be done once instead of multiply times in the
original.
diff -dpruN devfsd-1.3.22.orig/GNUmakefile devfsd-1.3.22/GNUmakefile
--- devfsd-1.3.22.orig/GNUmakefile Tue Jan 15 09:09:29 2002
+++ devfsd-1.3.22/GNUmakefile Sun Feb 17 22:03:11 2002
@@ -58,4 +58,5 @@ distclean: clean
# Dependencies: made by hand
-devfsd.o: devfsd.h version.h
+devfsd.o: devfsd.h strtry.h version.h
+compat_name.o: strtry.h
diff -dpruN devfsd-1.3.22.orig/compat_name.c devfsd-1.3.22/compat_name.c
--- devfsd-1.3.22.orig/compat_name.c Mon Jan 21 02:05:57 2002
+++ devfsd-1.3.22/compat_name.c Sun Feb 17 22:34:04 2002
@@ -71,6 +71,7 @@
# include <string.h>
# include <ctype.h>
#endif
+#include "strtry.h"
#ifndef IDE6_MAJOR /* In case we're building with an ancient kernel */
# define IDE6_MAJOR 88
@@ -137,35 +138,31 @@ const char *get_old_name (const char *de
*/
{
const char *compat_name = NULL;
- char *ptr;
+ char *ptr, *rsl = strrchr (devname, '/') + 1;/* right slash + 1 */
struct translate_struct *trans;
for (trans = translate_table; trans->match != NULL; ++trans)
- {
- size_t len = strlen (trans->match);
-
- if (strncmp (devname, trans->match, len) == 0)
+ if (ptr = strtry (devname, trans->match))
{
- if (trans->format == NULL) return (devname + len);
- sprintf (buffer, trans->format, devname + len);
+ if (trans->format == NULL) return (ptr);
+ sprintf (buffer, trans->format, ptr);
return (buffer);
}
- }
- if (strncmp (devname, "sbp/", 4) == 0)
+ if (strtry (devname, "sbp/"))
{
sprintf (buffer, "sbpcd%u", minor);
compat_name = buffer;
}
- else if (strncmp (devname, "scsi/", 5) == 0)
+ else if (strtry (devname, "scsi/"))
{ /* All SCSI devices */
if (strcmp (devname + namelen - 7, "generic") == 0)
{
sprintf (buffer, "sg%u", minor);
compat_name = buffer;
}
- else if (strncmp (ptr = (strrchr (devname, '/') + 1), "mt", 2) == 0)
+ else if (ptr = strtry (rsl, "mt"))
{
- char mode = ptr[2];
+ char mode = *ptr;
if (mode == 'n') mode = '\0';
sprintf (buffer, "nst%u%c", minor & 0x1f, mode);
@@ -179,15 +176,15 @@ const char *get_old_name (const char *de
}
else if (strcmp (devname + namelen - 4, "disc") == 0)
compat_name = write_old_sd_name (buffer, major, minor, "");
- else if (strncmp (ptr = (strrchr (devname, '/') + 1), "part", 4) == 0)
- compat_name = write_old_sd_name (buffer, major, minor, ptr + 4);
+ else if (ptr = strtry (rsl, "part"))
+ compat_name = write_old_sd_name (buffer, major, minor, ptr);
return (compat_name);
}
- else if (strncmp (devname, "ide/host", 8) == 0)
+ else if (strtry (devname, "ide/host"))
{ /* All IDE devices */
- if (strncmp (ptr = (strrchr (devname, '/') + 1), "mt", 2) == 0)
+ if (ptr = strtry (rsl, "mt"))
{
- sprintf (buffer, "%sht%d", ptr + 2, minor & 0x7f);
+ sprintf (buffer, "%sht%d", ptr, minor & 0x7f);
compat_name = buffer;
}
else if (strcmp (devname + namelen - 4, "disc") == 0)
@@ -196,10 +193,10 @@ const char *get_old_name (const char *de
get_old_ide_name (major, minor) );
compat_name = buffer;
}
- else if (strncmp (ptr = (strrchr (devname, '/') + 1), "part", 4) == 0)
+ else if (ptr = strtry (rsl, "part"))
{
sprintf (buffer, "hd%c%s",
- get_old_ide_name (major, minor), ptr + 4);
+ get_old_ide_name (major, minor), ptr);
compat_name = buffer;
}
else if (strcmp (devname + namelen - 2, "cd") == 0)
@@ -210,20 +207,20 @@ const char *get_old_name (const char *de
}
return (compat_name);
}
- else if (strncmp (devname, "vcc/", 4) == 0)
+ else if (ptr = strtry (devname, "vcc/"))
{
- sprintf (buffer, "vcs%s", devname + 4);
+ sprintf (buffer, "vcs%s", ptr);
if (buffer[3] == '0') buffer[3] = '\0';
compat_name = buffer;
}
- else if (strncmp (devname, "pty/", 4) == 0)
+ else if (ptr = strtry (devname, "pty/"))
{
- int index = atoi (devname + 5);
+ int index = atoi (ptr + 1);
const char *pty1 = "pqrstuvwxyzabcde";
const char *pty2 = "0123456789abcdef";
sprintf (buffer, "%cty%c%c",
- (devname[4] == 'm') ? 'p' : 't',
+ (*ptr == 'm') ? 'p' : 't',
pty1[index >> 4], pty2[index & 0x0f]);
compat_name = buffer;
}
diff -dpruN devfsd-1.3.22.orig/devfsd.c devfsd-1.3.22/devfsd.c
--- devfsd-1.3.22.orig/devfsd.c Mon Jan 21 02:07:31 2002
+++ devfsd-1.3.22/devfsd.c Sun Feb 17 21:58:18 2002
@@ -273,6 +273,7 @@
#include <rpcsvc/yp_prot.h>
#include <karma.h>
#include "devfsd.h"
+#include "strtry.h"
#include "version.h"
#ifndef RTLD_DEFAULT /* Libc 5 doesn't define it, but it works */
@@ -1416,7 +1417,7 @@ static void action_compat (const struct
{
const char *compat_name = NULL;
const char *dest_name = info->devname;
- char *ptr;
+ char *ptr, *rsl = strrchr (info->devname, '/') + 1;/* right slash + 1 */
char compat_buf[STRING_LENGTH], dest_buf[STRING_LENGTH];
static char function_name[] = "action_compat";
@@ -1430,22 +1431,21 @@ static void action_compat (const struct
break;
case AC_MKNEWCOMPAT:
case AC_RMNEWCOMPAT:
- if (strncmp (info->devname, "scsi/", 5) == 0)
+ if (ptr = strtry (info->devname, "scsi/"))
{
int mode, host, bus, target, lun;
- sscanf (info->devname + 5, "host%d/bus%d/target%d/lun%d/",
+ sscanf (ptr, "host%d/bus%d/target%d/lun%d/",
&host, &bus, &target, &lun);
compat_name = compat_buf;
snprintf (dest_buf, sizeof (dest_buf), "../%s", info->devname);
dest_name = dest_buf;
- if (strncmp (ptr = (strrchr (info->devname, '/') + 1), "mt", 2)
- == 0)
+ if (ptr = strtry (rsl, "mt"))
{
char rewind = info->devname[info->namelen - 1];
if (rewind != 'n') rewind = '\0';
- switch (ptr[2])
+ switch (*ptr)
{
default:
mode = 0;
@@ -1472,36 +1472,33 @@ static void action_compat (const struct
else if (strcmp (info->devname + info->namelen - 4, "disc") == 0)
sprintf (compat_buf, "sd/c%db%dt%du%d",
host, bus, target, lun);
- else if (strncmp (ptr = (strrchr (info->devname, '/') + 1), "part",
- 4) == 0)
+ else if (ptr = strtry (rsl, "part"))
sprintf ( compat_buf, "sd/c%db%dt%du%dp%d",
- host, bus, target, lun, atoi (ptr + 4) );
+ host, bus, target, lun, atoi (ptr) );
else compat_name = NULL;
}
- else if (strncmp (info->devname, "ide/host", 8) == 0)
+ else if (ptr = strtry (info->devname, "ide/host"))
{
int host, bus, target, lun;
- sscanf (info->devname + 4, "host%d/bus%d/target%d/lun%d/",
+ sscanf (ptr, "%d/bus%d/target%d/lun%d/",
&host, &bus, &target, &lun);
compat_name = compat_buf;
- snprintf (dest_buf, sizeof (dest_buf), "../%s", info->devname + 4);
+ snprintf (dest_buf, sizeof (dest_buf), "../%s", ptr - 4);
dest_name = dest_buf;
if (strcmp (info->devname + info->namelen - 4, "disc") == 0)
sprintf (compat_buf, "ide/hd/c%db%dt%du%d",
host, bus, target, lun);
- else if (strncmp (ptr = (strrchr (info->devname, '/') + 1), "part",
- 4) == 0)
+ else if (ptr = strtry (rsl, "part"))
sprintf ( compat_buf, "ide/hd/c%db%dt%du%dp%d",
- host, bus, target, lun, atoi (ptr + 4) );
+ host, bus, target, lun, atoi (ptr) );
else if (strcmp (info->devname + info->namelen - 2, "cd") == 0)
sprintf (compat_buf, "ide/cd/c%db%dt%du%d",
host, bus, target,lun);
- else if (strncmp (ptr = (strrchr (info->devname, '/') + 1), "mt",
- 2) == 0)
+ else if (ptr = strtry (rsl, "mt"))
snprintf (compat_buf, sizeof (compat_buf),
"ide/mt/c%db%dt%du%d%s",
- host, bus, target, lun, ptr + 2);
+ host, bus, target, lun, ptr);
else compat_name = NULL;
}
break;
diff -dpruN devfsd-1.3.22.orig/strtry.h devfsd-1.3.22/strtry.h
--- devfsd-1.3.22.orig/strtry.h Thu Jan 1 05:00:00 1970
+++ devfsd-1.3.22/strtry.h Sun Feb 17 21:38:10 2002
@@ -0,0 +1,11 @@
+/*
+ Tries if a string begins from some prefix. Returns an address of a
+ char after that prefix or NULL.
+*/
+extern inline
+char *strtry(const char *s, const char *try)
+{
+ char c;
+ do if (!(c= *try++)) return (char*)s;
+ while (*s++ == c); return NULL;
+}
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