Bug#721975: HURD support, build fails, maybe an easy fix [patch]

[Daniel Pocock]

Package: rrdtool
Version: 1.4.7-2

I notice that the HURD build is failing with an error about PATH_MAX

This is a common issue.  PATH_MAX doesn't exist in HURD and it is very
trivial to work around

Full build log:

https://buildd.debian.org/status/fetch.php?pkg=rrdtool&arch=hurd-i386&ver=1.4.7-2&stamp=1343897555

Error:

rrd_client.c: In function 'rrdc_update':
rrd_client.c:586:18: error: 'PATH_MAX' undeclared (first use in this function)
rrd_client.c:586:18: note: each undeclared identifier is reported only once for 
each function it appears in
rrd_client.c:586:8: warning: unused variable 'file_path' [-Wunused-variable]
rrd_client.c: In function 'rrdc_flush':
rrd_client.c:647:18: error: 'PATH_MAX' undeclared (first use in this function)
rrd_client.c:647:8: warning: unused variable 'file_path' [-Wunused-variable]
make[3]: *** [rrd_client.lo] Error 1
make[2]: *** [all-recursive] Error 1
make[1]: *** [all] Error 2
make: *** [build-arch-stamp] Error 2




Discussion:

http://www.gnu.org/software/hurd/community/gsoc/project_ideas/maxpath.html


Potential solution:

http://www.gnu.org/software/hurd/hurd/porting/guidelines.html#PATH_MAX_tt_MAX_PATH_tt_MAXPATHL

Attached is an example of a patch from another project, it appears easy enough 
to cut and paste into rrd_client.c




--- cpulimit-1.1.orig/cpulimit.c	2005-06-27 00:15:23.000000000 +0000
+++ cpulimit-1.1/cpulimit.c	2006-08-07 10:14:37.000000000 +0000
@@ -134,6 +134,22 @@ done:
 
 }
 
+char* xreadlink(const char *filename) {
+        int nchars;
+        int size = 1024;
+        char *buffer;
+        if ((buffer=(char*)malloc(size))==NULL)
+                return NULL;
+        while ((nchars=readlink(filename,buffer,size))<size) {
+                if (nchars<0)
+                        return NULL;
+                buffer=realloc(buffer,size);
+                size *= 2;
+        }
+        buffer[nchars]='\0';
+        return buffer;
+}
+
 //this function periodically scans process list and looks for executable path names
 //it should be executed in a low priority context, since precise timing does not matter
 //if a process is found then its pid is returned
@@ -148,7 +164,7 @@ int getpidof(const char *process) {
 	}
 
 	char exelink[20];
-	char exepath[PATH_MAX+1];
+	char *exepath = NULL;
 	int pid=0;
 	int i=0;
 
@@ -169,8 +185,9 @@ int getpidof(const char *process) {
 			pid=atoi(dit->d_name);
 			if (pid>0) {
 				sprintf(exelink,"/proc/%d/exe",pid);
-				int size=readlink(exelink,exepath,sizeof(exepath));
-				if (size>0) {
+				exepath=xreadlink(exelink);
+				if (exepath) {
+					size_t size = strlen(exepath);
 					int found=0;
 					if (process[0]=='/' && strncmp(exepath,process,size)==0 && size==strlen(process)) {
 						//process starts with / then it's an absolute path
@@ -191,6 +208,7 @@ int getpidof(const char *process) {
 							fprintf(stderr,"Error: Process %d detected, but you don't have permission to control it\n",pid);
 						}
 					}
+					free(exepath);
 				}
 			}
 		}