Dynamically scale the ST_UID size to support 32-bit UIDs

While most Unix-like systems use 16-bit user IDs,
Linux supports 32-bit UIDs since version 2.6.
UIDs above 65535 are used for UID namespacing of containers,
where a container has its own set of 16-bit user IDs.
Processes in such containers will have (much) larger UIDs than 65535.

Because the current format strings for `ST_UID` and `USER`
are `%5d` and `%9d` respectively, processes with such UIDs
lead to misaligned columns.

Dynamically scale the `ST_UID` column and increase the size of `USER`
to 10 characters (length of UINT32_MAX) to ensure that the user ID always fits.

Additionally: clean up how the titlebuffer size calculation and ensure
the PID column has a minimum size of 5.

1 files changed, 19 insertions, 5 deletions

diff --git a/ProcessList.c b/ProcessList.c
index 1ce6b76d..c4c759da 100644
--- a/ProcessList.c
+++ b/ProcessList.c
@@ -105,13 +105,19 @@ static const char* alignedProcessFieldTitle(const ProcessList* this, ProcessFiel
    if (!title)
       return "- ";
 
-   if (!Process_fields[field].pidColumn)
-      return title;
+   if (Process_fields[field].pidColumn) {
+      static char titleBuffer[PROCESS_MAX_PID_DIGITS + sizeof(" ")];
+      xSnprintf(titleBuffer, sizeof(titleBuffer), "%*s ", Process_pidDigits, title);
+      return titleBuffer;
+   }
 
-   static char titleBuffer[PROCESS_MAX_PID_DIGITS + /* space */ 1 + /* null-terminator */ + 1];
-   xSnprintf(titleBuffer, sizeof(titleBuffer), "%*s ", Process_pidDigits, title);
+   if (field == ST_UID) {
+      static char titleBuffer[PROCESS_MAX_UID_DIGITS + sizeof(" ")];
+      xSnprintf(titleBuffer, sizeof(titleBuffer), "%*s ", Process_uidDigits, title);
+      return titleBuffer;
+   }
 
-   return titleBuffer;
+   return title;
 }
 
 void ProcessList_printHeader(const ProcessList* this, RichString* header) {
@@ -626,10 +632,15 @@ void ProcessList_scan(ProcessList* this, bool pauseProcessUpdate) {
 
    ProcessList_goThroughEntries(this, false);
 
+   uid_t maxUid = 0;
    for (int i = Vector_size(this->processes) - 1; i >= 0; i--) {
       Process* p = (Process*) Vector_get(this->processes, i);
       Process_makeCommandStr(p);
 
+      // keep track of the highest UID for column scaling
+      if (p->st_uid > maxUid)
+         maxUid = p->st_uid;
+
       if (p->tombStampMs > 0) {
          // remove tombed process
          if (this->monotonicMs >= p->tombStampMs) {
@@ -647,6 +658,9 @@ void ProcessList_scan(ProcessList* this, bool pauseProcessUpdate) {
       }
    }
 
+   // Set UID column width based on max UID.
+   Process_setUidColumnWidth(maxUid);
+
    if (this->settings->treeView) {
       // Clear out the hashtable to avoid any left-over processes from previous build
       //