Re: [PATCHv9 2.6.35-rc4-tip 10/13] perf: Re-Add make_absolute_path

[Arnaldo Carvalho de Melo <acme@infradead.org>]

Em Mon, Jul 12, 2010 at 04:04:12PM +0530, Srikar Dronamraju escreveu:
> perf: Re-Add make_absolute_path
> 
> perf probe for uprobes would use make_absolute_path.
> make_absolute_path can be used to convert a file name to a dso name.
> 
> so if user specifies the function to be traced as malloc@/lib/libc.so.6
> it needs to be converted to malloc@libc-2.5.so

Isn't this the other way around? I.e. "if the user specifies
malloc@libc-2.5.so it needs to be converted to malloc@/lib/libc.so.6"?

Also please remove the xstrdup and die calls from this function, we're
trying to get rid of all such 'panic' like functions so that we can
librarize as much code as possible.
 
> This patch reverts a part of a41794cdd7ee94a5199e14f642c26d649d383fa5

> Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> ---
> 
>  tools/perf/util/abspath.c |   81 +++++++++++++++++++++++++++++++++++++++++++++
>  tools/perf/util/cache.h   |    1 +
>  2 files changed, 82 insertions(+), 0 deletions(-)
> 
> 
> diff --git a/tools/perf/util/abspath.c b/tools/perf/util/abspath.c
> index 0e76aff..0a985fd 100644
> --- a/tools/perf/util/abspath.c
> +++ b/tools/perf/util/abspath.c
> @@ -1,5 +1,86 @@
>  #include "cache.h"
>  
> +/*
> + * Do not use this for inspecting *tracked* content.  When path is a
> + * symlink to a directory, we do not want to say it is a directory when
> + * dealing with tracked content in the working tree.
> + */
> +static int is_directory(const char *path)
> +{
> +	struct stat st;
> +	return !stat(path, &st) && S_ISDIR(st.st_mode);
> +}
> +
> +/* We allow "recursive" symbolic links. Only within reason, though. */
> +#define MAXDEPTH 5
> +
> +const char *make_absolute_path(const char *path)
> +{
> +	static char bufs[2][PATH_MAX + 1], *buf = bufs[0], *next_buf = bufs[1];
> +	char cwd[1024] = "";
> +	int buf_index = 1, len;
> +
> +	int depth = MAXDEPTH;
> +	char *last_elem = NULL;
> +	struct stat st;
> +
> +	if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
> +		die("Too long path: %.*s", 60, path);
> +
> +	while (depth--) {
> +		if (!is_directory(buf)) {
> +			char *last_slash = strrchr(buf, '/');
> +			if (last_slash) {
> +				*last_slash = '\0';
> +				last_elem = xstrdup(last_slash + 1);
> +			} else {
> +				last_elem = xstrdup(buf);
> +				*buf = '\0';
> +			}
> +		}
> +
> +		if (*buf) {
> +			if (!*cwd && !getcwd(cwd, sizeof(cwd)))
> +				die("Could not get current working directory");
> +
> +			if (chdir(buf))
> +				die("Could not switch to '%s'", buf);
> +		}
> +		if (!getcwd(buf, PATH_MAX))
> +			die("Could not get current working directory");
> +
> +		if (last_elem) {
> +			len = strlen(buf);
> +
> +			if (len + strlen(last_elem) + 2 > PATH_MAX)
> +				die("Too long path name: '%s/%s'",
> +						buf, last_elem);
> +			buf[len] = '/';
> +			strcpy(buf + len + 1, last_elem);
> +			free(last_elem);
> +			last_elem = NULL;
> +		}
> +
> +		if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
> +			len = readlink(buf, next_buf, PATH_MAX);
> +			if (len < 0)
> +				die("Invalid symlink: %s", buf);
> +			if (PATH_MAX <= len)
> +				die("symbolic link too long: %s", buf);
> +			next_buf[len] = '\0';
> +			buf = next_buf;
> +			buf_index = 1 - buf_index;
> +			next_buf = bufs[buf_index];
> +		} else
> +			break;
> +	}
> +
> +	if (*cwd && chdir(cwd))
> +		die("Could not change back to '%s'", cwd);
> +
> +	return buf;
> +}
> +
>  static const char *get_pwd_cwd(void)
>  {
>  	static char cwd[PATH_MAX + 1];
> diff --git a/tools/perf/util/cache.h b/tools/perf/util/cache.h
> index 27e9ebe..0dfed40 100644
> --- a/tools/perf/util/cache.h
> +++ b/tools/perf/util/cache.h
> @@ -73,6 +73,7 @@ static inline int is_absolute_path(const char *path)
>  	return path[0] == '/';
>  }
>  
> +const char *make_absolute_path(const char *path);
>  const char *make_nonrelative_path(const char *path);
>  char *strip_path_suffix(const char *path, const char *suffix);
>