check for fgets/fscanf return values

diff --git a/slstatus.c b/slstatus.c
index b5924469933bed5352a17ee646d327de98a5d84f..af26fe7019ee28d5f389351ceab71942ceb01580 100644 (file)
--- a/slstatus.c
+++ b/slstatus.c
@@ -99,7 +99,7 @@ bprintf(const char *fmt, ...)
 static const char *
 battery_perc(const char *bat)
 {
-       int perc;
+       int n, perc;
        char path[PATH_MAX];
        FILE *fp;
 
@@ -109,8 +109,10 @@ battery_perc(const char *bat)
                warn("Failed to open file %s", path);
                return UNKNOWN_STR;
        }
-       fscanf(fp, "%i", &perc);
+       n = fscanf(fp, "%i", &perc);
        fclose(fp);
+       if (n != 1)
+               return UNKNOWN_STR;
 
        return bprintf("%d", perc);
 }
@@ -120,7 +122,7 @@ battery_power(const char *bat)
 {
        char path[PATH_MAX];
        FILE *fp;
-       int watts;
+       int n, watts;
 
        snprintf(path, sizeof(path), "%s%s%s", "/sys/class/power_supply/", bat, "/power_now");
        fp = fopen(path, "r");
@@ -128,8 +130,10 @@ battery_power(const char *bat)
                warn("Failed to open file %s", path);
                return UNKNOWN_STR;
        }
-       fscanf(fp, "%i", &watts);
+       n = fscanf(fp, "%i", &watts);
        fclose(fp);
+       if (n != 1)
+               return UNKNOWN_STR;
 
        return bprintf("%d", (watts + 500000) / 1000000);
 }
@@ -140,6 +144,7 @@ battery_state(const char *bat)
        char path[PATH_MAX];
        char state[12];
        FILE *fp;
+       int n;
 
        snprintf(path, sizeof(path), "%s%s%s", "/sys/class/power_supply/", bat, "/status");
        fp = fopen(path, "r");
@@ -147,8 +152,10 @@ battery_state(const char *bat)
                warn("Failed to open file %s", path);
                return UNKNOWN_STR;
        }
-       fscanf(fp, "%12s", state);
+       n = fscanf(fp, "%12s", state);
        fclose(fp);
+       if (n != 1)
+               return UNKNOWN_STR;
 
        if (strcmp(state, "Charging") == 0) {
                return "+";
@@ -166,7 +173,7 @@ battery_state(const char *bat)
 static const char *
 cpu_freq(void)
 {
-       int freq;
+       int n, freq;
        FILE *fp;
 
        fp = fopen("/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq", "r");
@@ -174,8 +181,10 @@ cpu_freq(void)
                warn("Failed to open file /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq");
                return UNKNOWN_STR;
        }
-       fscanf(fp, "%i", &freq);
+       n = fscanf(fp, "%i", &freq);
        fclose(fp);
+       if (n != 1)
+               return UNKNOWN_STR;
 
        return bprintf("%d", (freq + 500) / 1000);
 }
@@ -183,7 +192,7 @@ cpu_freq(void)
 static const char *
 cpu_perc(void)
 {
-       int perc;
+       int n, perc;
        long double a[4], b[4];
        FILE *fp;
 
@@ -192,8 +201,10 @@ cpu_perc(void)
                warn("Failed to open file /proc/stat");
                return UNKNOWN_STR;
        }
-       fscanf(fp, "%*s %Lf %Lf %Lf %Lf", &a[0], &a[1], &a[2], &a[3]);
+       n = fscanf(fp, "%*s %Lf %Lf %Lf %Lf", &a[0], &a[1], &a[2], &a[3]);
        fclose(fp);
+       if (n != 4)
+               return UNKNOWN_STR;
 
        delay++;
        sleep(delay);
@@ -203,8 +214,10 @@ cpu_perc(void)
                warn("Failed to open file /proc/stat");
                return UNKNOWN_STR;
        }
-       fscanf(fp, "%*s %Lf %Lf %Lf %Lf", &b[0], &b[1], &b[2], &b[3]);
+       n = fscanf(fp, "%*s %Lf %Lf %Lf %Lf", &b[0], &b[1], &b[2], &b[3]);
        fclose(fp);
+       if (n != 4)
+               return UNKNOWN_STR;
 
        perc = 100 * ((b[0]+b[1]+b[2]) - (a[0]+a[1]+a[2])) / ((b[0]+b[1]+b[2]+b[3]) - (a[0]+a[1]+a[2]+a[3]));
        return bprintf("%d", perc);
@@ -280,7 +293,7 @@ disk_used(const char *mnt)
 static const char *
 entropy(void)
 {
-       int num;
+       int n, num;
        FILE *fp;
 
        fp= fopen("/proc/sys/kernel/random/entropy_avail", "r");
@@ -288,8 +301,10 @@ entropy(void)
                warn("Failed to open file /proc/sys/kernel/random/entropy_avail");
                return UNKNOWN_STR;
        }
-       fscanf(fp, "%d", &num);
+       n = fscanf(fp, "%d", &num);
        fclose(fp);
+       if (n != 1)
+               return UNKNOWN_STR;
 
        return bprintf("%d", num);
 }
@@ -392,14 +407,17 @@ ram_free(void)
 {
        long free;
        FILE *fp;
+       int n;
 
        fp = fopen("/proc/meminfo", "r");
        if (fp == NULL) {
                warn("Failed to open file /proc/meminfo");
                return UNKNOWN_STR;
        }
-       fscanf(fp, "MemFree: %ld kB\n", &free);
+       n = fscanf(fp, "MemFree: %ld kB\n", &free);
        fclose(fp);
+       if (n != 1)
+               return UNKNOWN_STR;
 
        return bprintf("%f", (float)free / 1024 / 1024);
 }
@@ -415,13 +433,19 @@ ram_perc(void)
                warn("Failed to open file /proc/meminfo");
                return UNKNOWN_STR;
        }
-       fscanf(fp, "MemTotal: %ld kB\n", &total);
-       fscanf(fp, "MemFree: %ld kB\n", &free);
-       fscanf(fp, "MemAvailable: %ld kB\nBuffers: %ld kB\n", &buffers, &buffers);
-       fscanf(fp, "Cached: %ld kB\n", &cached);
+       if (fscanf(fp, "MemTotal: %ld kB\n", &total) != 1 ||
+           fscanf(fp, "MemFree: %ld kB\n", &free) != 1 ||
+           fscanf(fp, "MemAvailable: %ld kB\nBuffers: %ld kB\n",
+                  &buffers, &buffers) != 2 ||
+           fscanf(fp, "Cached: %ld kB\n", &cached) != 1)
+               goto scanerr;
        fclose(fp);
 
        return bprintf("%d", 100 * ((total - free) - (buffers + cached)) / total);
+
+scanerr:
+       fclose(fp);
+       return UNKNOWN_STR;
 }
 
 static const char *
@@ -429,14 +453,17 @@ ram_total(void)
 {
        long total;
        FILE *fp;
+       int n;
 
        fp = fopen("/proc/meminfo", "r");
        if (fp == NULL) {
                warn("Failed to open file /proc/meminfo");
                return UNKNOWN_STR;
        }
-       fscanf(fp, "MemTotal: %ld kB\n", &total);
+       n = fscanf(fp, "MemTotal: %ld kB\n", &total);
        fclose(fp);
+       if (n != 1)
+               return UNKNOWN_STR;
 
        return bprintf("%f", (float)total / 1024 / 1024);
 }
@@ -452,19 +479,25 @@ ram_used(void)
                warn("Failed to open file /proc/meminfo");
                return UNKNOWN_STR;
        }
-       fscanf(fp, "MemTotal: %ld kB\n", &total);
-       fscanf(fp, "MemFree: %ld kB\n", &free);
-       fscanf(fp, "MemAvailable: %ld kB\nBuffers: %ld kB\n", &buffers, &buffers);
-       fscanf(fp, "Cached: %ld kB\n", &cached);
+       if (fscanf(fp, "MemTotal: %ld kB\n", &total) != 1 ||
+           fscanf(fp, "MemFree: %ld kB\n", &free) != 1 ||
+           fscanf(fp, "MemAvailable: %ld kB\nBuffers: %ld kB\n",
+                  &buffers, &buffers) != 2 ||
+           fscanf(fp, "Cached: %ld kB\n", &cached) != 1)
+               goto scanerr;
        fclose(fp);
 
        return bprintf("%f", (float)(total - free - buffers - cached) / 1024 / 1024);
+
+scanerr:
+       fclose(fp);
+       return UNKNOWN_STR;
 }
 
 static const char *
 run_command(const char *cmd)
 {
-       char *nlptr;
+       char *p;
        FILE *fp;
 
        fp = popen(cmd, "r");
@@ -472,10 +505,12 @@ run_command(const char *cmd)
                warn("Failed to get command output for %s", cmd);
                return UNKNOWN_STR;
        }
-       fgets(buf, sizeof(buf) - 1, fp);
+       p = fgets(buf, sizeof(buf) - 1, fp);
        pclose(fp);
-       if ((nlptr = strrchr(buf, '\n')) != NULL)
-               nlptr[0] = '\0';
+       if (!p)
+               return UNKNOWN_STR;
+       if ((p = strrchr(buf, '\n')) != NULL)
+               p[0] = '\0';
 
        return buf[0] ? buf : UNKNOWN_STR;
 }
@@ -613,7 +648,7 @@ swap_used(void)
 static const char *
 temp(const char *file)
 {
-       int temp;
+       int n, temp;
        FILE *fp;
 
        fp = fopen(file, "r");
@@ -621,8 +656,10 @@ temp(const char *file)
                warn("Failed to open file %s", file);
                return UNKNOWN_STR;
        }
-       fscanf(fp, "%d", &temp);
+       n = fscanf(fp, "%d", &temp);
        fclose(fp);
+       if (n != 1)
+               return UNKNOWN_STR;
 
        return bprintf("%d", temp / 1000);
 }
@@ -697,8 +734,8 @@ vol_perc(const char *card)
 static const char *
 wifi_perc(const char *iface)
 {
-       int perc;
-       char *datastart;
+       int i, perc;
+       char *p, *datastart;
        char path[PATH_MAX];
        char status[5];
        FILE *fp;
@@ -709,9 +746,9 @@ wifi_perc(const char *iface)
                warn("Failed to open file %s", path);
                return UNKNOWN_STR;
        }
-       fgets(status, 5, fp);
+       p = fgets(status, 5, fp);
        fclose(fp);
-       if(strcmp(status, "up\n") != 0) {
+       if(!p || strcmp(status, "up\n") != 0) {
                return UNKNOWN_STR;
        }
 
@@ -721,10 +758,13 @@ wifi_perc(const char *iface)
                return UNKNOWN_STR;
        }
 
-       fgets(buf, sizeof(buf) - 1, fp);
-       fgets(buf, sizeof(buf) - 1, fp);
-       fgets(buf, sizeof(buf) - 1, fp);
+       for (i = 0; i < 3; i++) {
+               if (!(p = fgets(buf, sizeof(buf) - 1, fp)))
+                       break;
+       }
        fclose(fp);
+       if (i < 2 || !p)
+               return UNKNOWN_STR;
 
        if ((datastart = strstr(buf, iface)) == NULL)
                return UNKNOWN_STR;