[pmg-devel] [PATCH v2 pmg-log-tracker 1/5] rfc3339: move timezone offset compatibility code to old time parser

[Mira Limbeck <m.limbeck@proxmox.com>]

The compatibility code was added to the new rfc3339 code path temporarily so
that the old code path would not be changed before the PMG 8 release.

Now move it to the old time format code to make sure the rfc3339 code path
works as expected. Since we have all the information we need (year, month,
day, hours, minutes, seconds, timezone), there's no need for a workaround in
this code path.

As a side effect of parsing the time format `YYYY-MM-DD HH:MM:SS` in
localtime, it's now possible to parse an rfc3339 compliant format
(except for fractional seconds).
Because of changes to time parsing, we now have to use strftime_local
from the proxmox_time crate to print the time correctly.

The change needs to be accompanied by one in pmg-api MailTracker.pmg to
keep the time displayed in the GUI the same for the old time format, and
correct for the new rfc3339 format.

Signed-off-by: Mira Limbeck <m.limbeck@proxmox.com>
---
I've tested it locally with both old timestamp format and new one, but
running it on more logs would not hurt

Since we use only the start time to calculate the timezone offset, it
will not be reliable in all cases, especially when the end time offset
differs from the start time.

v2:
 - removed TODO line
 - fixed start-/endtime offset mentioned by @stoiko on the rfc
 - added rfc3339 start-/endtime handling as suggested by @dominik since
   it eases parsing the YYYY-MM-DD HH:MM:SS format as localtime rather
   than UTC
 - added tests in another patch


 src/main.rs | 58 ++++++++++++++++++++++++++++++++---------------------
 src/time.rs | 23 ++++++++++++++++++++-
 2 files changed, 57 insertions(+), 24 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index e7aeeb4..82d5657 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -9,7 +9,7 @@ use std::io::BufReader;
 use std::io::BufWriter;
 use std::io::Write;
 
-use anyhow::{bail, Error};
+use anyhow::{bail, Context, Error};
 use flate2::read;
 use libc::time_t;
 
@@ -90,12 +90,12 @@ fn main() -> Result<(), Error> {
 
     println!(
         "# Start: {} ({})",
-        time::strftime(c_str!("%F %T"), &parser.start_tm)?,
+        proxmox_time::strftime_local("%F %T", parser.options.start)?,
         parser.options.start
     );
     println!(
         "# End: {} ({})",
-        time::strftime(c_str!("%F %T"), &parser.end_tm)?,
+        proxmox_time::strftime_local("%F %T", parser.options.end)?,
         parser.options.end
     );
 
@@ -1787,7 +1787,11 @@ impl Parser {
                 line,
                 self.current_year,
                 self.current_month,
-                self.timezone_offset,
+                // use start time for timezone offset in parse_time_no_year rather than the
+                // timezone offset of the current time
+                // this is required for cases where current time is in standard time, while start
+                // time is in summer time or the other way around
+                self.start_tm.tm_gmtoff,
             ) {
                 Some(t) => t,
                 None => continue,
@@ -1920,12 +1924,14 @@ impl Parser {
         }
 
         if let Some(start) = args.opt_value_from_str::<_, String>(["-s", "--starttime"])? {
-            if let Ok(res) = time::strptime(&start, c_str!("%F %T")) {
-                self.options.start = res.as_utc_to_epoch();
-                self.start_tm = res;
-            } else if let Ok(res) = time::strptime(&start, c_str!("%s")) {
-                self.options.start = res.as_utc_to_epoch();
-                self.start_tm = res;
+            if let Ok(epoch) = proxmox_time::parse_rfc3339(&start).or_else(|_| {
+                time::date_to_rfc3339(&start).and_then(|s| proxmox_time::parse_rfc3339(&s))
+            }) {
+                self.options.start = epoch;
+                self.start_tm = time::Tm::at_local(epoch).context("failed to parse start time")?;
+            } else if let Ok(epoch) = start.parse::<time_t>() {
+                self.options.start = epoch;
+                self.start_tm = time::Tm::at_local(epoch).context("failed to parse start time")?;
             } else {
                 bail!("failed to parse start time");
             }
@@ -1939,12 +1945,14 @@ impl Parser {
         }
 
         if let Some(end) = args.opt_value_from_str::<_, String>(["-e", "--endtime"])? {
-            if let Ok(res) = time::strptime(&end, c_str!("%F %T")) {
-                self.options.end = res.as_utc_to_epoch();
-                self.end_tm = res;
-            } else if let Ok(res) = time::strptime(&end, c_str!("%s")) {
-                self.options.end = res.as_utc_to_epoch();
-                self.end_tm = res;
+            if let Ok(epoch) = proxmox_time::parse_rfc3339(&end).or_else(|_| {
+                time::date_to_rfc3339(&end).and_then(|s| proxmox_time::parse_rfc3339(&s))
+            }) {
+                self.options.end = epoch;
+                self.end_tm = time::Tm::at_local(epoch).context("failed to parse end time")?;
+            } else if let Ok(epoch) = end.parse::<time_t>() {
+                self.options.end = epoch;
+                self.end_tm = time::Tm::at_local(epoch).context("failed to parse end time")?;
             } else {
                 bail!("failed to parse end time");
             }
@@ -2196,11 +2204,11 @@ fn parse_time(
     cur_month: i64,
     timezone_offset: time_t,
 ) -> Option<(time_t, &'_ [u8])> {
-    parse_time_with_year(data, timezone_offset)
-        .or_else(|| parse_time_no_year(data, cur_year, cur_month))
+    parse_time_with_year(data)
+        .or_else(|| parse_time_no_year(data, cur_year, cur_month, timezone_offset))
 }
 
-fn parse_time_with_year(data: &'_ [u8], timezone_offset: time_t) -> Option<(time_t, &'_ [u8])> {
+fn parse_time_with_year(data: &'_ [u8]) -> Option<(time_t, &'_ [u8])> {
     let mut timestamp_buffer = [0u8; 25];
 
     let count = data.iter().take_while(|b| **b != b' ').count();
@@ -2227,13 +2235,17 @@ fn parse_time_with_year(data: &'_ [u8], timezone_offset: time_t) -> Option<(time
     match proxmox_time::parse_rfc3339(unsafe {
         std::str::from_utf8_unchecked(&timestamp_buffer[0..timestamp_len])
     }) {
-        // TODO handle timezone offset in old code path instead
-        Ok(ltime) => Some((ltime + timezone_offset, data)),
+        Ok(ltime) => Some((ltime, data)),
         Err(_err) => None,
     }
 }
 
-fn parse_time_no_year(data: &'_ [u8], cur_year: i64, cur_month: i64) -> Option<(time_t, &'_ [u8])> {
+fn parse_time_no_year(
+    data: &'_ [u8],
+    cur_year: i64,
+    cur_month: i64,
+    timezone_offset: time_t,
+) -> Option<(time_t, &'_ [u8])> {
     if data.len() < 15 {
         return None;
     }
@@ -2338,7 +2350,7 @@ fn parse_time_no_year(data: &'_ [u8], cur_year: i64, cur_month: i64) -> Option<(
         _ => &data[1..],
     };
 
-    Some((ltime, data))
+    Some((ltime - timezone_offset, data))
 }
 
 type ByteSlice<'a> = &'a [u8];
diff --git a/src/time.rs b/src/time.rs
index 5851496..9a2ce73 100644
--- a/src/time.rs
+++ b/src/time.rs
@@ -149,7 +149,8 @@ pub fn strftime(format: &CStr, tm: &Tm) -> Result<String, Error> {
 
 /// Wrapper around `strptime(3)` to parse time strings.
 pub fn strptime(time: &str, format: &CStr) -> Result<Tm, Error> {
-    let mut out = MaybeUninit::<libc::tm>::uninit();
+    // zero memory because strptime does not necessarily initialize tm_isdst, tm_gmtoff and tm_zone
+    let mut out = MaybeUninit::<libc::tm>::zeroed();
 
     let time = CString::new(time).map_err(|_| format_err!("time string contains nul bytes"))?;
 
@@ -167,3 +168,23 @@ pub fn strptime(time: &str, format: &CStr) -> Result<Tm, Error> {
 
     Ok(Tm(unsafe { out.assume_init() }))
 }
+
+pub fn date_to_rfc3339(date: &str) -> Result<String, Error> {
+    // parse the YYYY-MM-DD HH:MM:SS format for the timezone info
+    let ltime = strptime(date, c_str!("%F %T"))?;
+
+    // strptime assume it is in UTC, but we want to interpret it as local time and get the timezone
+    // offset (tm_gmtoff) which we can then append to be able to parse it as rfc3339
+    let ltime = Tm::at_local(ltime.as_utc_to_epoch())?;
+
+    let mut s = date.replacen(' ', "T", 1);
+    if ltime.tm_gmtoff != 0 {
+        let sign = if ltime.tm_gmtoff < 0 { '-' } else { '+' };
+        let minutes = (ltime.tm_gmtoff / 60) % 60;
+        let hours = ltime.tm_gmtoff / (60 * 60);
+        s.push_str(&format!("{}{:02}:{:02}", sign, hours, minutes));
+    } else {
+        s.push('Z');
+    }
+    Ok(s)
+}
-- 
2.39.2