Fix get_from_pipe potentially reading more bytes than its buffer size

.gitignore

@@ -58,6 +58,7 @@ doc/texinfo.tex
 doc/version.texi
 examples/affinity
 examples/df
+examples/disk
 examples/diskio
 examples/first
 examples/free

examples/Makefile.am

@@ -11,7 +11,7 @@ AM_LDFLAGS			= $(LIBGTOP_EXTRA_LIBS)
 
 noinst_PROGRAMS	= 	first second pprint procargs df netlist \
 			  mountlist procmap netload sysdeps timings \
-			  openfiles smp proclist free wd affinity diskio sysinfo
+			  openfiles smp proclist free wd affinity disk diskio sysinfo
 
 first_SOURCES		= first.c
 first_LDADD		= $(top_builddir)/lib/libgtop-2.0.la

sysdeps/linux/disk.c

@@ -235,7 +235,7 @@ glibtop_get_disk_s (glibtop *server, glibtop_disk *buf)
 
 	file_to_buffer (server, buffer, sizeof buffer, FILENAME);
 
-	get_from_pipe (map_buffer, CMD_PIPE);
+	get_from_pipe (map_buffer, STAT_BUFSIZ, CMD_PIPE);
 
 	/*
 	 * GLOBAL

sysdeps/linux/glibtop_private.c

@@ -58,17 +58,15 @@ skip_token (const char *p)
 
 
 void
-get_from_pipe (char *buffer, const char *cmd)
+get_from_pipe (char *buffer, const size_t bufsiz, const char *cmd)
 {
 	FILE* fp;
-	long psize;
 
 	fp = popen (cmd, "r");
 
-	fseek (fp, 0, SEEK_END);
-	psize = ftell (fp);
-	fseek (fp, 0, SEEK_SET);
-	fread(buffer,1,psize,fp);
+	size_t psize = fread(buffer,1,bufsiz,fp);
+	if (psize == bufsiz)
+		g_warning("Read bufsiz bytes, there may be more");
 
 	pclose (fp);
 }

sysdeps/linux/glibtop_private.h

@@ -62,7 +62,7 @@ skip_line (const char *p)
 }
 
 void
-get_from_pipe (char *buffer, const char *cmd);
+get_from_pipe (char *buffer, const size_t bufsiz, const char *cmd);
 
 /*
  * Smart strtoul which handles binary suffixes