Package ganeti :: Package utils :: Module text

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Module text

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Utility functions for manipulating or working with text.

Classes

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ShellWriter
Helper class to write scripts with indentation.

LineSplitter
Splits data chunks into lines separated by newline.

Functions

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None or str

MatchNameComponent(key, name_list, case_sensitive=True)
Try to match a name against a list.

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_DnsNameGlobHelper(match)
Helper function for DnsNameGlobPattern.

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string

DnsNameGlobPattern(pattern)
Generates regular expression from DNS name globbing pattern.

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str

FormatUnit(value, units)
Formats an incoming number of MiB with the appropriate unit.

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ParseUnit(input_string)
Tries to extract number and scale from the given string.

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str

ShellQuote(value)
Quotes shell argument according to POSIX.

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str

ShellQuoteArgs(args)
Quotes a list of shell arguments.

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str

GenerateSecret(numbytes=20)
Generates a random secret.

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_MakeMacAddrRegexp(octets)
Builds a regular expression for verifying MAC addresses.

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_MacAddressCheck(check_re, mac, msg)
Checks a MAC address using a regular expression.

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string

NormalizeAndValidateMac(mac)
Normalizes and check if a MAC address is valid and contains six octets.

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string

NormalizeAndValidateThreeOctetMacPrefix(mac)
Normalizes a potential MAC address prefix (three octets).

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str

SafeEncode(text)
Return a 'safe' version of a source string.

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string

UnescapeAndSplit(text, sep=",")
Split and unescape a string based on a given separator.

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CommaJoin(names)
Nicely join a set of identifiers.

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FormatTime(val, usecs=None)
Formats a time value.

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string

FormatSeconds(secs)
Formats seconds for easier reading.

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boolean

IsValidShellParam(word)
Verifies is the given word is safe from the shell's p.o.v.

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str

BuildShellCmd(template, *args)
Build a safe shell command line from the given arguments.

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string

FormatOrdinal(value)
Formats a number as an ordinal in the English language.

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string

Truncate(text, length)
Truncate string and add ellipsis if needed.

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list

FilterEmptyLinesAndComments(text)
Filters empty lines and comments from a line-based string.

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list of string

FormatKeyValue(data)
Formats a dictionary as "key=value" parameters.

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Variables

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_PARSEUNIT_REGEX = re.compile(r"^([.\d]+)\s*([a-zA-Z]+)?$")
Unit checker regexp

_SHELL_UNQUOTED_RE = re.compile("^[-.,=:/_+@A-Za-z0-9]+$")
Characters which don't need to be quoted for shell commands

_SHELLPARAM_REGEX = re.compile(r"^[-a-zA-Z0-9._+/:%@]+$")
Shell param checker regexp

_ASCII_ELLIPSIS = "..."
ASCII equivalent of unicode character 'HORIZONTAL ELLIPSIS' (U+2026)

_MAC_ADDR_OCTET_RE = r"[0-9a-f]{2}"
MAC address octet

_MAC_CHECK_RE = _MakeMacAddrRegexp(6)
Regular expression for full MAC address

_MAC_PREFIX_CHECK_RE = _MakeMacAddrRegexp(3)
Regular expression for half a MAC address

Imports: re, os, time, collections, errors

Function Details

[hide private]

MatchNameComponent(key, name_list, case_sensitive=True)

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Try to match a name against a list.

This function will try to match a name like test1 against a list like ['test1.example.com', 'test2.example.com', ...]. Against this list, 'test1' as well as 'test1.example' will match, but not 'test1.ex'. A multiple match will be considered as no match at all (e.g. 'test1' against ['test1.example.com', 'test1.example.org']), except when the key fully matches an entry (e.g. 'test1' against ['test1', 'test1.example.com']).

Parameters:

key (str) - the name to be searched
name_list (list) - the list of strings against which to search the key
case_sensitive (boolean) - whether to provide a case-sensitive match

Returns: None or str

None if there is no match or if there are multiple matches, otherwise the element from the list which matches

_DnsNameGlobHelper(match)

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Helper function for DnsNameGlobPattern.

Returns regular expression pattern for parts of the pattern.

DnsNameGlobPattern(pattern)

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Generates regular expression from DNS name globbing pattern.

A DNS name globbing pattern (e.g. *.site) is converted to a regular expression. Escape sequences or ranges (e.g. [a-z]) are not supported.

Matching always starts at the leftmost part. An asterisk (*) matches all characters except the dot (.) separating DNS name parts. A question mark (?) matches a single character except the dot (.).

Parameters:

pattern (string) - DNS name globbing pattern

Returns: string

Regular expression

FormatUnit(value, units)

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Formats an incoming number of MiB with the appropriate unit.

Parameters:

value (int) - integer representing the value in MiB (1048576)
units (char) - the type of formatting we should do:
- 'h' for automatic scaling
- 'm' for MiBs
- 'g' for GiBs
- 't' for TiBs

Returns: str

the formatted value (with suffix)

ParseUnit(input_string)

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Tries to extract number and scale from the given string.

Input must be in the format NUMBER+ [DOT NUMBER+] SPACE* [UNIT]. If no unit is specified, it defaults to MiB. Return value is always an int in MiB.

ShellQuote(value)

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Quotes shell argument according to POSIX.

Parameters:

value (str) - the argument to be quoted

Returns: str

the quoted value

ShellQuoteArgs(args)

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Quotes a list of shell arguments.

Parameters:

args (list) - list of arguments to be quoted

Returns: str

the quoted arguments concatenated with spaces

GenerateSecret(numbytes=20)

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Generates a random secret.

This will generate a pseudo-random secret returning an hex string (so that it can be used where an ASCII string is needed).

Parameters:

numbytes - the number of bytes which will be represented by the returned string (defaulting to 20, the length of a SHA1 hash)

Returns: str

an hex representation of the pseudo-random sequence

_MakeMacAddrRegexp(octets)

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Builds a regular expression for verifying MAC addresses.

Parameters:

octets (integer) - How many octets to expect (1-6)

Returns:

Compiled regular expression

_MacAddressCheck(check_re, mac, msg)

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Checks a MAC address using a regular expression.

Parameters:

check_re - Compiled regular expression as returned by re.compile
mac (string) - MAC address to be validated
msg (string) - Error message (%s will be replaced with MAC address)

NormalizeAndValidateMac(mac)

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Normalizes and check if a MAC address is valid and contains six octets.

Checks whether the supplied MAC address is formally correct. Accepts colon-separated format only. Normalize it to all lower case.

Parameters:

mac (string) - MAC address to be validated

Returns: string

Normalized and validated MAC address

Raises:

errors.OpPrereqError - If the MAC address isn't valid

NormalizeAndValidateThreeOctetMacPrefix(mac)

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Normalizes a potential MAC address prefix (three octets).

Checks whether the supplied string is a valid MAC address prefix consisting of three colon-separated octets. The result is normalized to all lower case.

Parameters:

mac (string) - Prefix to be validated

Returns: string

Normalized and validated prefix

Raises:

errors.OpPrereqError - If the MAC address prefix isn't valid

SafeEncode(text)

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Return a 'safe' version of a source string.

This function mangles the input string and returns a version that should be safe to display/encode as ASCII. To this end, we first convert it to ASCII using the 'backslashreplace' encoding which should get rid of any non-ASCII chars, and then we process it through a loop copied from the string repr sources in the python; we don't use string_escape anymore since that escape single quotes and backslashes too, and that is too much; and that escaping is not stable, i.e. string_escape(string_escape(x)) != string_escape(x).

Parameters:

text (str or unicode) - input data

Returns: str

a safe version of text

UnescapeAndSplit(text, sep=",")

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Split and unescape a string based on a given separator.

This function splits a string based on a separator where the separator itself can be escape in order to be an element of the elements. The escaping rules are (assuming coma being the separator):

a plain , separates the elements
a sequence \\, (double backslash plus comma) is handled as a backslash plus a separator comma
a sequence \, (backslash plus comma) is handled as a non-separator comma

Parameters:

text (string) - the string to split
text (string) - the separator
sep (string)

Returns: string

a list of strings

CommaJoin(names)

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Nicely join a set of identifiers.

Parameters:

names - set, list or tuple

Returns:

a string with the formatted results

FormatTime(val, usecs=None)

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Formats a time value.

Parameters:

val (float or None) - Timestamp as returned by time.time() (seconds since Epoch, 1970-01-01 00:00:00 UTC)

Returns:

a string value or N/A if we don't have a valid timestamp

FormatSeconds(secs)

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Formats seconds for easier reading.

Parameters:

secs (number) - Number of seconds

Returns: string

Formatted seconds (e.g. "2d 9h 19m 49s")

IsValidShellParam(word)

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Verifies is the given word is safe from the shell's p.o.v.

This means that we can pass this to a command via the shell and be sure that it doesn't alter the command line and is passed as such to the actual command.

Note that we are overly restrictive here, in order to be on the safe side.

Parameters:

word (str) - the word to check

Returns: boolean

True if the word is 'safe'

BuildShellCmd(template, *args)

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Build a safe shell command line from the given arguments.

This function will check all arguments in the args list so that they are valid shell parameters (i.e. they don't contain shell metacharacters). If everything is ok, it will return the result of template % args.

Parameters:

template (str) - the string holding the template for the string formatting

Returns: str

the expanded command line

FormatOrdinal(value)

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Formats a number as an ordinal in the English language.

E.g. the number 1 becomes "1st", 22 becomes "22nd".

Parameters:

value (integer) - Number

Returns: string

Truncate(text, length)

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Truncate string and add ellipsis if needed.

Parameters:

text (string) - Text
length (integer) - Desired length

Returns: string

Truncated text

FilterEmptyLinesAndComments(text)

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Filters empty lines and comments from a line-based string.

Whitespace is also removed from the beginning and end of all lines.

Parameters:

text (string) - Input string

Returns: list

FormatKeyValue(data)

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Formats a dictionary as "key=value" parameters.

The keys are sorted to have a stable order.

Parameters:

data (dict)

Returns: list of string