[Xapian-tickets] [Xapian] #665: Avoid C library functions not guaranteed to be thread-safe

[Xapian]

#665: Avoid C library functions not guaranteed to be thread-safe
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 Reporter:  olly         |             Owner:  olly
     Type:  defect       |            Status:  new
 Priority:  normal       |         Milestone:  1.4.x
Component:  Library API  |           Version:  1.3.2
 Severity:  normal       |        Resolution:
 Keywords:               |        Blocked By:
 Blocking:               |  Operating System:  All
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Comment (by olly):

 I've now eliminated all uses of `atoi()` and `strtol()` in the library
 itself.

 Current status:

  * `getenv()` - used to read things like `XAPIAN_FLUSH_THRESHOLD`.
  * `strerror()` (but only if there's no thread-safe alternative).
  * `strtod()` - `weight/weightinternal.h` parsing double parameters,
 `api/valuerangeproc.cc` `NumberRangeProcessor::operator()` - also means
 that behaviour depends on the locale, which is probably not always
 desirable.  C++17 provides
 [https://en.cppreference.com/w/cpp/utility/from_chars std::from_chars()]
 which we could use if available.  Do we want to provide a way to allow `,`
 as decimal point though?

 Also to do:

  * Add section to the developer docs about this
  * Add checks to `xapian-check-patch` to prevent more calls to problematic
 functions from being introduced into the library code

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Ticket URL: <https://trac.xapian.org/ticket/665#comment:17>
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