lscpu: improve --sysroot code

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/sys-utils/lscpu.c b/sys-utils/lscpu.c
index 3f1c32756fbfedcf06be68c51b483a57c2fd8e02..d554f9b2effec63211d33c748a295772517a3ce7 100644 (file)
--- a/sys-utils/lscpu.c
+++ b/sys-utils/lscpu.c
@@ -36,12 +36,12 @@
 #define CACHE_MAX 100
 
 /* /sys paths */
-#define _PATH_SYS_SYSTEM       "sys/devices/system"
+#define _PATH_SYS_SYSTEM       "/sys/devices/system"
 #define _PATH_SYS_CPU0         _PATH_SYS_SYSTEM "/cpu/cpu0"
-#define _PATH_PROC_XEN         "proc/xen"
+#define _PATH_PROC_XEN         "/proc/xen"
 #define _PATH_PROC_XENCAP      _PATH_PROC_XEN "/capabilities"
-#define _PATH_PROC_CPUINFO     "proc/cpuinfo"
-#define _PATH_PROC_PCIDEVS     "proc/bus/pci/devices"
+#define _PATH_PROC_CPUINFO     "/proc/cpuinfo"
+#define _PATH_PROC_PCIDEVS     "/proc/bus/pci/devices"
 
 int have_topology;
 int have_cache;
@@ -121,8 +121,13 @@ struct lscpu_desc {
        int     *nodecpu;
 };
 
-char pathbuf[PATH_MAX] = "/";
+static size_t sysrootlen;
+static char pathbuf[PATH_MAX];
 
+static const char *path_create(const char *path, ...)
+               __attribute__ ((__format__ (__printf__, 1, 2)));
+static FILE *path_fopen(const char *mode, int exit_on_err, const char *path, ...)
+               __attribute__ ((__format__ (__printf__, 3, 4)));
 static void path_getstr(char *result, size_t len, const char *path, ...)
                __attribute__ ((__format__ (__printf__, 3, 4)));
 static int path_getnum(const char *path, ...)
@@ -132,20 +137,53 @@ static int path_exist(const char *path, ...)
 static int path_sibling(const char *path, ...)
                __attribute__ ((__format__ (__printf__, 1, 2)));
 
+static const char *
+path_vcreate(const char *path, va_list ap)
+{
+       if (sysrootlen)
+               vsnprintf(pathbuf + sysrootlen,
+                         sizeof(pathbuf) - sysrootlen, path, ap);
+       else
+               vsnprintf(pathbuf, sizeof(pathbuf), path, ap);
+       return pathbuf;
+}
+
+static const char *
+path_create(const char *path, ...)
+{
+       const char *p;
+       va_list ap;
+
+       va_start(ap, path);
+       p = path_vcreate(path, ap);
+       va_end(ap);
+
+       return p;
+}
+
 static FILE *
-xfopen(const char *path, const char *mode)
+path_vfopen(const char *mode, int exit_on_error, const char *path, va_list ap)
 {
-       FILE *fd = fopen(path, mode);
-       if (!fd)
-               err(EXIT_FAILURE, _("error: %s"), path);
-       return fd;
+       FILE *f;
+       const char *p = path_vcreate(path, ap);
+
+       f = fopen(p, mode);
+       if (!f && exit_on_error)
+               err(EXIT_FAILURE, _("error: cannot open %s"), p);
+       return f;
 }
 
 static FILE *
-path_vfopen(const char *mode, const char *path, va_list ap)
+path_fopen(const char *mode, int exit_on_error, const char *path, ...)
 {
-       vsnprintf(pathbuf, sizeof(pathbuf), path, ap);
-       return xfopen(pathbuf, mode);
+       FILE *fd;
+       va_list ap;
+
+       va_start(ap, path);
+       fd = path_vfopen("r", exit_on_error, path, ap);
+       va_end(ap);
+
+       return fd;
 }
 
 static void
@@ -155,7 +193,7 @@ path_getstr(char *result, size_t len, const char *path, ...)
        va_list ap;
 
        va_start(ap, path);
-       fd = path_vfopen("r", path, ap);
+       fd = path_vfopen("r", 1, path, ap);
        va_end(ap);
 
        if (!fgets(result, len, fd))
@@ -175,14 +213,14 @@ path_getnum(const char *path, ...)
        int result;
 
        va_start(ap, path);
-       fd = path_vfopen("r", path, ap);
+       fd = path_vfopen("r", 1, path, ap);
        va_end(ap);
 
        if (fscanf(fd, "%d", &result) != 1) {
                if (ferror(fd))
-                       err(EXIT_FAILURE, _("error: %s"), pathbuf);
+                       err(EXIT_FAILURE, _("failed to read: %s"), pathbuf);
                else
-                       errx(EXIT_FAILURE, _("error parse: %s"), pathbuf);
+                       errx(EXIT_FAILURE, _("parse error: %s"), pathbuf);
        }
        fclose(fd);
        return result;
@@ -192,12 +230,13 @@ static int
 path_exist(const char *path, ...)
 {
        va_list ap;
+       const char *p;
 
        va_start(ap, path);
-       vsnprintf(pathbuf, sizeof(pathbuf), path, ap);
+       p = path_vcreate(path, ap);
        va_end(ap);
 
-       return access(pathbuf, F_OK) == 0;
+       return access(p, F_OK) == 0;
 }
 
 char *
@@ -220,7 +259,7 @@ path_sibling(const char *path, ...)
        va_list ap;
 
        va_start(ap, path);
-       fp = path_vfopen("r", path, ap);
+       fp = path_vfopen("r", 1, path, ap);
        va_end(ap);
 
        while ((c = fgetc(fp)) != EOF) {
@@ -282,7 +321,7 @@ int lookup(char *line, char *pattern, char **value)
 static void
 read_basicinfo(struct lscpu_desc *desc)
 {
-       FILE *fp = xfopen(_PATH_PROC_CPUINFO, "r");
+       FILE *fp = path_fopen("r", 1, _PATH_PROC_CPUINFO);
        char buf[BUFSIZ];
        struct utsname utsbuf;
 
@@ -336,7 +375,7 @@ has_pci_device(int vendor, int device)
        int num, fn, ven, dev;
        int res = 1;
 
-       f = fopen(_PATH_PROC_PCIDEVS, "r");
+       f = path_fopen("r", 0, _PATH_PROC_PCIDEVS);
        if (!f)
                return 0;
 
@@ -428,9 +467,9 @@ read_hypervisor(struct lscpu_desc *desc)
                /* hvm */
                desc->virtype = VIRT_FULL;
 
-       else if (!access(_PATH_PROC_XEN, F_OK)) {
+       else if (path_exist(_PATH_PROC_XEN)) {
                /* Xen para-virt or dom0 */
-               FILE *fd = fopen(_PATH_PROC_XENCAP, "r");
+               FILE *fd = path_fopen("r", 0, _PATH_PROC_XENCAP);
                int dom0 = 0;
 
                if (fd) {
@@ -474,10 +513,11 @@ read_cache(struct lscpu_desc *desc)
        DIR *dp;
        struct dirent *dir;
        int level, type;
+       const char *p = path_create(_PATH_SYS_CPU0 "/cache");
 
-       dp = opendir(_PATH_SYS_CPU0 "/cache");
+       dp = opendir(p);
        if (dp == NULL)
-               err(EXIT_FAILURE, _("error: %s"), _PATH_SYS_CPU0 "/cache");
+               err(EXIT_FAILURE, _("error: %s"), p);
 
        while ((dir = readdir(dp)) != NULL) {
                if (!strcmp(dir->d_name, ".")
@@ -542,17 +582,17 @@ static void
 check_system(void)
 {
        /* Read through sysfs. */
-       if (access(_PATH_SYS_SYSTEM, F_OK))
+       if (!path_exist(_PATH_SYS_SYSTEM))
                errx(EXIT_FAILURE,
-                    _("error: /sys filesystem is not accessable."));
+                    _("error: %s is not accessable."), pathbuf);
 
-       if (!access(_PATH_SYS_SYSTEM "/node", F_OK))
+       if (path_exist(_PATH_SYS_SYSTEM "/node"))
                have_node = 1;
 
-       if (!access(_PATH_SYS_CPU0 "/topology/thread_siblings", F_OK))
+       if (path_exist(_PATH_SYS_CPU0 "/topology/thread_siblings"))
                have_topology = 1;
 
-       if (!access(_PATH_SYS_CPU0 "/cache", F_OK))
+       if (path_exist(_PATH_SYS_CPU0 "/cache"))
                have_cache = 1;
 }
 
@@ -732,17 +772,15 @@ int main(int argc, char *argv[])
                        parsable = 1;
                        break;
                case 's':
+                       sysrootlen = strlen(optarg);
                        strncpy(pathbuf, optarg, sizeof(pathbuf));
+                       pathbuf[sizeof(pathbuf) - 1] = '\0';
                        break;
                default:
                        usage(EXIT_FAILURE);
                }
        }
 
-       if (chdir(pathbuf) == -1)
-               errx(EXIT_FAILURE,
-                    _("error: change working directory to %s."), pathbuf);
-
        memset(desc, 0, sizeof(*desc));
 
        check_system();