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authorDave Reisner <dreisner@archlinux.org>2012-04-25 22:27:19 -0400
committerDan McGee <dan@archlinux.org>2012-06-25 23:39:12 -0500
commitb58489d29a1898a4bff1b5da6ca4bfb14003dbfe (patch)
tree5c42f704cc671136ef43972cfdee1274e620e65f /scripts/library
parente183522e3168c4a31103b3c7910fa8d29333fb5a (diff)
scripts/library: add human_to_size
This is a bash wrapper around an awk function that parses human readable sizes and returns their representative values in bytes, as a string. A small test harness is added to validate the functionality. Signed-off-by: Dave Reisner <dreisner@archlinux.org>
Diffstat (limited to 'scripts/library')
-rw-r--r--scripts/library/README8
-rw-r--r--scripts/library/human_to_size.sh51
2 files changed, 59 insertions, 0 deletions
diff --git a/scripts/library/README b/scripts/library/README
index c71c0714..44748ee2 100644
--- a/scripts/library/README
+++ b/scripts/library/README
@@ -27,3 +27,11 @@ Reccommended Usage:
Returns:
0: parse success
1: parse failure (error message supplied)
+
+human_to_size.sh:
+A function to convert human readable sizes (such as "5.3 GiB") to raw byte
+equivalents. base10 and base2 suffixes are supported, case sensitively. If
+successful, the converted byte value is written to stdout and the function
+returns 0. If an error occurs, nothing in written and the function returns 1.
+Results may be inaccurate when using a broken implementation of awk, such
+as mawk or busybox awk.
diff --git a/scripts/library/human_to_size.sh b/scripts/library/human_to_size.sh
new file mode 100644
index 00000000..11613207
--- /dev/null
+++ b/scripts/library/human_to_size.sh
@@ -0,0 +1,51 @@
+human_to_size() {
+ awk -v human="$1" '
+ function trim(s) {
+ gsub(/^[[:space:]]+|[[:space:]]+$/, "", s)
+ return s
+ }
+
+ function parse_units(units) {
+ if (!units || units == "B")
+ return 1
+ if (match(units, /^.iB$/))
+ return 1024
+ if (match(units, /^.B$/))
+ return 1000
+ if (length(units) == 1)
+ return 1024
+
+ # parse failure: invalid base
+ return -1
+ }
+
+ function parse_scale(s) {
+ return index("BKMGTPE", s) - 1
+ }
+
+ function isnumeric(string) {
+ return match(string, /^[-+]?[[:digit:]]*(\.[[:digit:]]*)?/)
+ }
+
+ BEGIN {
+ # peel off the leading number as the size, fail on invalid number
+ human = trim(human)
+ if (isnumeric(human))
+ size = substr(human, RSTART, RLENGTH)
+ else
+ exit 1
+
+ # the trimmed remainder is assumed to be the units
+ units = trim(substr(human, RLENGTH + 1))
+
+ base = parse_units(units)
+ if (base < 0)
+ exit 1
+
+ scale = parse_scale(substr(units, 1, 1))
+ if (scale < 0)
+ exit 1
+
+ printf "%d\n", size * base^scale + (size + 0 > 0 ? 0.5 : -0.5)
+ }'
+}