[wiki] [sites] [slstatus][patch][dyn-battery] Another code rewrite || Lukas Lynch

From: <git_AT_suckless.org>
Date: Thu, 19 Feb 2026 01:33:59 +0100

commit c0b2b64ad8150a4afcd88e80a1d85644cfcc0fda
Author: Lukas Lynch <madi_AT_mxdi.xyz>
Date: Wed Feb 18 16:30:07 2026 -0800

    [slstatus][patch][dyn-battery] Another code rewrite

diff --git a/tools.suckless.org/slstatus/patches/dyn-battery/index.md b/tools.suckless.org/slstatus/patches/dyn-battery/index.md
index d06374f9..7f709b66 100644
--- a/tools.suckless.org/slstatus/patches/dyn-battery/index.md
+++ b/tools.suckless.org/slstatus/patches/dyn-battery/index.md
_AT_@ -14,7 +14,7 @@ state (%s), capacity (%s). Example:
 
 Download
 --------
-* [slstatus-dyn_battery-20260102-8723e8b.diff](slstatus-dyn_battery-20260102-8723e8b.diff)
+* [slstatus-dyn_battery-20260218-614c275.diff](slstatus-dyn_battery-20260218-614c275.diff)
 
 Author
 ------
diff --git a/tools.suckless.org/slstatus/patches/dyn-battery/slstatus-dyn_battery-20260102-8723e8b.diff b/tools.suckless.org/slstatus/patches/dyn-battery/slstatus-dyn_battery-20260102-8723e8b.diff
deleted file mode 100644
index 110eb85b..00000000
--- a/tools.suckless.org/slstatus/patches/dyn-battery/slstatus-dyn_battery-20260102-8723e8b.diff
+++ /dev/null
_AT_@ -1,185 +0,0 @@
-From 6316c8cb7b2b92098907943223ffe1a748359146 Mon Sep 17 00:00:00 2001
-From: Madison Lynch <madi_AT_mxdi.xyz>
-Date: Fri, 2 Jan 2026 04:33:17 -0800
-Subject: [PATCH] Code refactor + Improved memory safety
-
----
- Makefile                 |   1 +
- components/dyn_battery.c | 124 +++++++++++++++++++++++++++++++++++++++
- config.def.h             |   1 +
- slstatus.h               |   3 +
- 4 files changed, 129 insertions(+)
- create mode 100644 components/dyn_battery.c
-
-diff --git a/Makefile b/Makefile
-index 7a18274..d1b24dd 100644
---- a/Makefile
-+++ b/Makefile
-_AT_@ -11,6 +11,7 @@ COM =\
- 	components/cpu\
- 	components/datetime\
- 	components/disk\
-+	components/dyn_battery\
- 	components/entropy\
- 	components/hostname\
- 	components/ip\
-diff --git a/components/dyn_battery.c b/components/dyn_battery.c
-new file mode 100644
-index 0000000..cc87fc1
---- /dev/null
-+++ b/components/dyn_battery.c
-_AT_@ -0,0 +1,124 @@
-+/* Written by Lukas Lynch <madi_AT_mxdi.xyz> */
-+/* Only Linux is supported */
-+#include <stdio.h>
-+#include <stdlib.h>
-+#include <stdbool.h>
-+#include <string.h>
-+#include <dirent.h>
-+
-+#include "../util.h"
-+#include "../slstatus.h"
-+
-+#define BAT_PREFIX "BAT"
-+#define BAT_DIR "/sys/class/power_supply"
-+
-+static bool err;
-+static const char *err_str = "err";
-+
-+/**
-+* Calculates the number of digits in a given positive integer.
-+*/
-+static size_t
-+count_digits(const unsigned int input) {
-+    size_t count = 0;
-+    unsigned int n = input;
-+
-+    while(n/10 != 0)
-+        count++;
-+
-+    return count+1;
-+}
-+
-+/**
-+* Counts number of batteries detected by system.
-+*
-+* _AT_return Unsigned integer denoting the number of detected batteries
-+* _AT_author Lukas Lynch
-+*/
-+static unsigned int
-+count_batteries(void) {
-+    const size_t bat_prefix_s = strlen(BAT_PREFIX);
-+    DIR *dir = opendir(BAT_DIR);
-+    if(!dir) {
-+        fprintf(stderr, "dyn_battery: Failed to open %s
", BAT_DIR);
-+        err = true;
-+        return 0;
-+    }
-+
-+    unsigned int batc = 0;
-+    struct dirent *entry;
-+    while((entry = readdir(dir)))
-+        if(
-+            strlen(entry->d_name) > bat_prefix_s &&
-+            strncmp(entry->d_name, BAT_PREFIX, bat_prefix_s) == 0
-+        ) batc++;
-+
-+    (void) closedir(dir);
-+    return batc;
-+}
-+
-+/**
-+* Displays the status and capacity of a dynamic amount of batteries (i.e.
-+* laptops may have secondary external batteries).
-+*
-+* _AT_param  fmt format string to use for each battery display. ordered key:
-+*             %u: battery number || %s: battery state || %s battery capacity
-+* _AT_return string containing the status and capacities of all detected batteries
-+* _AT_author Lukas Lynch
-+*/
-+const char *
-+dyn_battery(const char *fmt) {
-+    err = false;
-+    const size_t fmt_s = strlen(fmt);
-+    const unsigned int batc = count_batteries();
-+
-+    if(err) // err set by count_batteries()
-+        return err_str;
-+
-+    if(batc == 0) 
-+        return NULL;
-+
-+    // We need the amount of digits in bat_c for displaying it in strings
-+    const size_t batc_digits = count_digits(batc);
-+
-+    char buf[
-+          (batc * (fmt_s - 2)) // bat count * (format string - "%u" format specifier)
-+        + (batc * batc_digits) // bat count * digits in bat count
-+        + 1                    // NULL byte
-+    ];
-+
-+    // Fill buffer with 0s, otherwise displacement calculations below can fail
-+    memset(buf, 0, sizeof(buf));
-+
-+    /*
-+    * The displacement variable will be updated with the current string length,
-+    * which is independent from the buffer size, in order to allow us to write
-+    * to the buffer without overwriting.
-+    */
-+    unsigned int displacement = 0;
-+    for(unsigned int i=0; i<batc; i++) {
-+        // Length of BAT_PREFIX + number of digits in bat count + 1 (NULL byte)
-+        char bat[strlen(BAT_PREFIX) + batc_digits + 1];
-+        (void) sprintf(bat, "%s%u", BAT_PREFIX, i);
-+
-+        // Add battery info to output buffer
-+        displacement += sprintf(
-+            buf + displacement, // Write into buffer after previous writes
-+            fmt,                // Format string specified by config.h
-+            i,
-+            battery_state(bat), // See components/battery.c
-+            battery_perc(bat)   // See components/battery.c
-+        );
-+
-+        // Add space between battery entries
-+        buf[displacement++] = ' ';
-+    }
-+
-+    // Remove extra space after last battery entry
-+    buf[--displacement] = '-+
-+    return bprintf("%s", buf);
-+}
-+
-+#undef BAT_DIR
-+#undef BAT_PREFIX
-\ No newline at end of file
-diff --git a/config.def.h b/config.def.h
-index 100093e..7f26909 100644
---- a/config.def.h
-+++ b/config.def.h
-_AT_@ -26,6 +26,7 @@ static const char unknown_str[] = "n/a";
-  * disk_perc           disk usage in percent           mountpoint path (/)
-  * disk_total          total disk space in GB          mountpoint path (/)
-  * disk_used           used disk space in GB           mountpoint path (/)
-+ * dyn_battery         displays the name, state and    format string (%u, %s, %s)
-  * entropy             available entropy               NULL
-  * gid                 GID of current user             NULL
-  * hostname            hostname                        NULL
-diff --git a/slstatus.h b/slstatus.h
-index 394281c..6beeaec 100644
---- a/slstatus.h
-+++ b/slstatus.h
-_AT_@ -21,6 +21,9 @@ const char *disk_perc(const char *path);
- const char *disk_total(const char *path);
- const char *disk_used(const char *path);
- 
-+/* dyn_battery */
-+const char *dyn_battery(const char *fmt);
-+
- /* entropy */
- const char *entropy(const char *unused);
- 
--- 
-2.52.0
-
diff --git a/tools.suckless.org/slstatus/patches/dyn-battery/slstatus-dyn_battery-20260218-614c275.diff b/tools.suckless.org/slstatus/patches/dyn-battery/slstatus-dyn_battery-20260218-614c275.diff
new file mode 100644
index 00000000..1355795f
--- /dev/null
+++ b/tools.suckless.org/slstatus/patches/dyn-battery/slstatus-dyn_battery-20260218-614c275.diff
_AT_@ -0,0 +1,141 @@
+From 5f04140fe8c73a96bae2a4eba899f2b114849673 Mon Sep 17 00:00:00 2001
+From: Lukas Lynch <madi_AT_mxdi.xyz>
+Date: Wed, 18 Feb 2026 16:20:25 -0800
+Subject: [PATCH] Displays status/capacity for a dynamic # of batteries
+
+---
+ Makefile                 |  1 +
+ components/dyn_battery.c | 80 ++++++++++++++++++++++++++++++++++++++++
+ config.def.h             |  1 +
+ slstatus.h               |  3 ++
+ 4 files changed, 85 insertions(+)
+ create mode 100644 components/dyn_battery.c
+
+diff --git a/Makefile b/Makefile
+index 7a18274..d1b24dd 100644
+--- a/Makefile
++++ b/Makefile
+_AT_@ -11,6 +11,7 @@ COM =\
+ 	components/cpu\
+ 	components/datetime\
+ 	components/disk\
++	components/dyn_battery\
+ 	components/entropy\
+ 	components/hostname\
+ 	components/ip\
+diff --git a/components/dyn_battery.c b/components/dyn_battery.c
+new file mode 100644
+index 0000000..7f49122
+--- /dev/null
++++ b/components/dyn_battery.c
+_AT_@ -0,0 +1,80 @@
++/* Written by Lukas Lynch <madi_AT_mxdi.xyz> */
++/* Only Linux is supported */
++#include <stdio.h>
++#include <string.h>
++#include <dirent.h>
++
++/* extern char buf[n] */
++#include "../util.h"
++
++/* See components/battery.c */
++const char *battery_state(const char *);
++const char *battery_perc(const char *);
++
++/*
++* This output buffer is global so we can just return its address, instead of
++* copying its contents to 'buf' (declared in slstatus.c) with bprintf().
++*/
++char out[sizeof(buf)];
++
++#if defined(__linux__)
++#define BAT_PREFIX "BAT"
++#define BAT_PREFIX_LEN sizeof(BAT_PREFIX)-1 // NULL byte included in sizeof()
++#define BAT_DIR "/sys/class/power_supply/"
++
++/**
++* Displays the status and capacity of a dynamic amount of batteries (i.e.
++* laptops with external/secondary batteries).
++*
++* _AT_param  fmt format string to use for each battery display. ordered key:
++*             %u: battery number || %s: battery state || %s battery capacity
++* _AT_return address of the output buffer, which contains the status and
++*         capacities of all detected batteries
++*/
++const char *
++dyn_battery(const char *fmt) {
++    *out = '++
++    DIR *dirp = opendir(BAT_DIR);
++    if(!dirp) {
++        fprintf(stderr, "dyn_battery: Failed to open %s
", BAT_DIR);
++        return "err";
++    }
++
++    unsigned int outp = 0, // Next free position in 'out'
++                 batn = 0; // Battery # (i.e. BAT0, BAT1, ...)
++    struct dirent *fp;     // Current file in 'dirp' readout
++
++    while((fp = readdir(dirp))) {
++        char *bat = fp->d_name; // Makes following code less ugly
++
++        if(
++            strlen(bat) > BAT_PREFIX_LEN &&
++            strncmp(bat, BAT_PREFIX, BAT_PREFIX_LEN) == 0
++        ) {
++            outp += sprintf(
++                out + outp,         // Starts after previous writes
++                fmt,                // Format string specified in config.h
++                batn++,             // 'batn' is decoupled from OS BAT#
++                battery_state(bat), // See components/battery.c
++                battery_perc(bat)   // See components/battery.c
++            );
++
++            // Add space between battery entries
++            buf[outp++] = ' ';
++        }
++    } // end while
++
++    if(closedir(dirp) != 0) {
++        fprintf(stderr, "dyn_battery: Failed to close %s.
", BAT_DIR);
++        return "err";
++    }
++
++    if(*out) {
++        out[--outp] = '++        return out;
++    } else return NULL;
++}
++#else // #if defined(__linux__)
++# error "dyn_battery: Only Linux is currently supported."
++#endif
+\ No newline at end of file
+diff --git a/config.def.h b/config.def.h
+index 100093e..7f26909 100644
+--- a/config.def.h
++++ b/config.def.h
+_AT_@ -26,6 +26,7 @@ static const char unknown_str[] = "n/a";
+  * disk_perc           disk usage in percent           mountpoint path (/)
+  * disk_total          total disk space in GB          mountpoint path (/)
+  * disk_used           used disk space in GB           mountpoint path (/)
++ * dyn_battery         displays the name, state and    format string (%u, %s, %s)
+  * entropy             available entropy               NULL
+  * gid                 GID of current user             NULL
+  * hostname            hostname                        NULL
+diff --git a/slstatus.h b/slstatus.h
+index 394281c..6beeaec 100644
+--- a/slstatus.h
++++ b/slstatus.h
+_AT_@ -21,6 +21,9 @@ const char *disk_perc(const char *path);
+ const char *disk_total(const char *path);
+ const char *disk_used(const char *path);
+ 
++/* dyn_battery */
++const char *dyn_battery(const char *fmt);
++
+ /* entropy */
+ const char *entropy(const char *unused);
+ 
+-- 
+2.53.0
+
Received on Thu Feb 19 2026 - 01:33:59 CET

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