An optimized dirname()

This commit is contained in:
Arun Prakash Jana 2017-04-01 17:32:58 +05:30
parent 7be7a6d215
commit 8f18c4049c
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GPG key ID: A75979F35C080412
2 changed files with 99 additions and 6 deletions

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@ -72,9 +72,15 @@ I chose to fork because:
- Associate PDF files with [zathura](https://pwmt.org/projects/zathura/) - Associate PDF files with [zathura](https://pwmt.org/projects/zathura/)
- Use environment variable `NNN_FALLBACK_OPENER` to open other non-associated files - Use environment variable `NNN_FALLBACK_OPENER` to open other non-associated files
- Removed `less` as default file opener (there is no universal standalone opener utility) - Removed `less` as default file opener (there is no universal standalone opener utility)
- Compilation - Optimizations
- Use `-O3` for compilation, fixed warnings - Efficient memory usage, 0 malloc()
- Complete redundant buffer removal
- All frequently used local chunks now static
- Removed some redundant string allocation and manipulation
- Simplified some roundabout procedures
- `-O3` level optimization, warning fixes
- Added compilation flag `-march=native` - Added compilation flag `-march=native`
- Massive binary size optimization
- Remove generated config.h on `make clean` - Remove generated config.h on `make clean`
- strip the final binary - strip the final binary

95
nnn.c
View file

@ -7,7 +7,6 @@
#include <dirent.h> #include <dirent.h>
#include <errno.h> #include <errno.h>
#include <fcntl.h> #include <fcntl.h>
#include <libgen.h>
#include <limits.h> #include <limits.h>
#include <locale.h> #include <locale.h>
#include <regex.h> #include <regex.h>
@ -93,9 +92,9 @@ typedef struct entry {
static struct entry *dents; static struct entry *dents;
static int ndents, cur; static int ndents, cur;
static int idle; static int idle;
static char *opener = NULL; static char *opener;
static char *fallback_opener = NULL; static char *fallback_opener;
static char *copier = NULL; static char *copier;
static const char* size_units[] = {"B", "K", "M", "G", "T", "P", "E", "Z", "Y"}; static const char* size_units[] = {"B", "K", "M", "G", "T", "P", "E", "Z", "Y"};
/* /*
@ -144,6 +143,29 @@ xrealloc(void *p, size_t size)
return p; return p;
} }
/*
* The poor man's implementation of memrchr().
* We are only looking for '/' in this program.
*/
static void *
xmemrchr(const void *s, int c, size_t n)
{
unsigned char *p;
unsigned char ch = (unsigned char)c;
if (!s || !n)
return NULL;
p = (unsigned char *)s + n - 1;
while(n--)
if ((*p--) == ch)
return ++p;
return NULL;
}
#if 0
/* Some implementations of dirname(3) may modify `path' and some /* Some implementations of dirname(3) may modify `path' and some
* return a pointer inside `path'. */ * return a pointer inside `path'. */
static char * static char *
@ -159,6 +181,71 @@ xdirname(const char *path)
strlcpy(out, p, sizeof(out)); strlcpy(out, p, sizeof(out));
return out; return out;
} }
#endif
/*
* The following dirname() implementation does not
* change the input. We use a copy of the original.
*
* Modified from the glibc (GNU LGPL) version.
*/
static char *
xdirname(const char *path)
{
static char name[PATH_MAX];
char *last_slash;
strlcpy(name, path, PATH_MAX);
/* Find last '/'. */
last_slash = name != NULL ? strrchr(name, '/') : NULL;
if (last_slash != NULL && last_slash != name && last_slash[1] == '\0') {
/* Determine whether all remaining characters are slashes. */
char *runp;
for (runp = last_slash; runp != name; --runp)
if (runp[-1] != '/')
break;
/* The '/' is the last character, we have to look further. */
if (runp != name)
last_slash = xmemrchr(name, '/', runp - name);
}
if (last_slash != NULL) {
/* Determine whether all remaining characters are slashes. */
char *runp;
for (runp = last_slash; runp != name; --runp)
if (runp[-1] != '/')
break;
/* Terminate the name. */
if (runp == name) {
/* The last slash is the first character in the string.
We have to return "/". As a special case we have to
return "//" if there are exactly two slashes at the
beginning of the string. See XBD 4.10 Path Name
Resolution for more information. */
if (last_slash == name + 1)
++last_slash;
else
last_slash = name + 1;
} else
last_slash = runp;
last_slash[0] = '\0';
} else {
/* This assignment is ill-designed but the XPG specs require to
return a string containing "." in any case no directory part
is found and so a static and constant string is required. */
name[0] = '.';
name[1] = '\0';
}
return name;
}
static void static void
spawn(char *file, char *arg, char *dir) spawn(char *file, char *arg, char *dir)